HOC GIA HOA]\G XUA]^ HAN - NGlTdl XAY 1\E]\ MONG CHO LICH HOC VIET NAM
L £ THANH LAN'
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am 1996, Giao sU Hoang Xuan Han ma't, Nha nude da truy tang eho Giao sU Huan chUdng Ddc lap hang Hai.Sau dd, vao nam 2000, Nha niide lai truy tang Giai thudng Ho Chi Minh vdi 3 tae pham: La Sdn Phu Ti, Ly Thiidng Kiet va Lich vd lich Viit Nam. Dd la 3 tac pham Sii hpc tieu bieu cua Giao su Hoang Xuan Han.
Cac tae pham Ly Thiidng Kiet va La San Phu TH la nhiing cud'n sii xae thiic, sau sic, ma tii lau da la mdt khudn mau vd~ mdt phiiPng phap hien dai de nghien cilu sii hpc d Viet Nam. Cud'n Lich vd lich Viit Nam (1) in nam 1982 da dat ndn mdng viing chic eho mdn Lieh hpc d Viet Nam. Day la mdt tae pham diic ket thanh qua nghien ciiu ve lich va dae biet la lich Viet Nam trong nhieu nam ciia Giao sii b i t dau tii nam 1944, khi vie't bai Lich vd lich ddi Li (2).
Thanh qua quan trpng nha't ciia Giao sU Hoang Xuan Han trong viec nghien ciiu Lich hoc la viec phat hien r a tii ra't xa xua, lich Viet Nam da khac lich Trung Qud'c.
1. Trong cac thu tich ed, khdng thay ndi ve mdt lich ed rieng eiia Viet Nam khae vdi lieh Trung Qud'c. Chiing ta ciing khdng tha'y cac nha bac hpc nhu Le Quy Ddn, Phan Huy Chii viet ve van de nay. Song,
trong thu tich cd, qua that eiing ed ddi chd phang phat ndi ve kha nang ed mdt lich ed Viet Nam, nhiing dieu dd cdn ra't md hd:
ching ban trong Nam ong mgng luc. Ho Nguyen Triing cd n h i c de'n Bach thi' thdng ky eua T r i n Nguyen Dan; hay Dgi Nam thiic luc ghi lai Idi tau ciia sii t h i n Nguyin Hiiu Than Idn vua Gia Long sau chuyen di sii ve vao nam 1810, r i n g ma'y tram nam qua lich ta theo mdt phdp cii, trong khi Trung Qude theo mpt phep mdi... That ra, chi gan day, sau khi da tim tha'y lich cd Viet Nam, chiing ta mdi hieu ro y nghia cua nhiing doan van dd. Tuy vay, tii lau nhieu ngUdi dpe Dgi Viet sH ky todn thii tha'y trong dd nhiing thang nhuan khdng cd trong lieh Trung Qud'c; da phan van, tii hdi:
hoac la sii gia ta ehep sai, hoac la lieh Viet Nam khac lich Trung Qud'c? Hp khdng tin Dai Viit sii ky todn thii ehep sai, nhUng Cling khdng tim dUdc bang ehiing ve" sii tdn tai cua mdt lich ed Vidt Nam.
Cho de'n g i n day, ra't nhieu ngUdi vin tin r i n g , khdng ed mdt lich cd Viet Nam.
Mdt ly do dPn gian la cd nhid'u ngudi da bd edng siie ra soan cac cudn lieh dd'i chieu lieh Duong vdi lich Am-DUdng d the ky trUdc deu chi diing lich Trung Qud'c. NhQng ' PGS-TS. Vien Cong nghe Thong tin - Vjgn Han lam KH&CN Viet Nam
jjoc g i i Ijoang Xu^n lian„. 23 ngudi khac tii nghT r i n g minh khdng cd
chuyen mdn ve Lich hpc, danh chiu. Ngay ea khi dUde tiep xiic vdi cae cud'n lich cd nam d thii vien, hp ciing khdng ngd dd la lieh Viet Nam, hoan toan khac lich Trung Qud'c, nen khdng khao ciiu ky. Cd hai nhdm nghidn ciiu da bi bd Id ed hdi: Nhdm tae gia bien soan Lich the ky XX vao nSm 1967 da tiing tidp xiic vdi cudn Hodng trieu Minh menh van nien thii ma khdng biet dd la cud'n hch Viet Nam. Nhdm tae gia bien soan cud'n Bdng dot chieu Am Diidng lich 2000 ndm vd nien bieu lich sii vao nam 1976 cd nhic den cudn Bach triing kinh (BTIQ (3) nhung ciing khdng khao ciiu ky de tim ra lich cd Viet Nam. Cung cd the ed ngiidi da tidn hanh khao ciiu, nhung khdng du kidn n h i n va kinh nghidm nen khdng di dd'n ket qua eudi ciing. Vet tich ve viec khao ciiu nay cdn liiu lai trong cud'n Khdm dinh vg,n nien thii (VNT) (4) vdi cac da'u khuyen dd 5 ta't ea cac thang nhuan cua 360 nam lich. Gid day ddc gia ed the xem dupe toan van hai cud'n Uch ed BTK (ban m) va VNT (ban in) qua i n anh trong cud'n Ndm trdm nam lich Viet Nam (1544-2043) (5) xua't ban nam 2010.
Them vao dd chung ta thiy, cac nUdc trong khu viic, hoac la diing lich An Dp, hoac la diing lieh Trung Qud'c; ndn it ngUdi nghi rang xa xUa Viet Nam da tiing cd mdt lich rieng.
Nam 1884, Hidp lide Giap Than (Patendtre) diidc kj', nUde Viet Nam bi chia lam ba xii, theo ba che' dp cai tri khac nhau;
Bic ky (Tonkin), Trung Ky (Annam) va Nam K$ (Cochinehine) n i m trong Ddng DUdng thudc Phap. Do nhu c i u quan ly hanh chinh, ngudi Phap d Bic Ky da soan nhiing cud'n lich doi chieu lich DUdng vdi lieh Am-DUdng b i n g chii Phap va che Qud'c ngfl. Cd le dau tidn la Deloustal, R. soan cud'n Calendrier annamite - fran^ais de 1802 a 1916 (Viet • Phap hdp lich) in nam
1908. Cud'n nay dupe tai ban ed bd sung vao cae nam 1915, 1922 va 1935. Rdi de'n Cordier, G. va Le Diic Hoat soan cudn Concordance des calendriers lunaire et solaire de 1802 a 2010 (Doi chieu lieh Am va lich Dudng tii 1802 dd'n 2010). Cd le nhflng cudn lieh nay thdng dung d Bic Ky va ca d Nam Ky niia. Ca ba tac gia deu cd quan niem sai lam r i n g xiia nay Viet Nam chi diing lich Trung Qud'c, hp khdng biet r i n g ngay thud dd d Trung Ky, Kham Thien Giam eua nha Nguyen v i n tii soan la'y mdt lich Am-Diidng rieng cho Viet Nam va b i n g nam nha vua van ban phat lich dd;
nha't la hp khdng biet lich nha Nguyen cac nam tii 1802 de'n 1812 hoan toan khac lich nha Thanh va hp la'y lieh nha Thanh in vao trong sach cua hp. Do chii Qud'c ngii d i n d i n thay the' ehii Nho va cae cud'n lich tren lai ra't phd dung, khien eho sU ngd nhan nay trd thanh thien kie'n sai l i m ching nhiing dd'i vdi ngUdi ngoai qud'c ma ca dd'i vdi ngudi Viet Nam.
2. Nam 1944, hpe gia Hoang Xuan Han doc dUde mdt bdn ehep tay cud'n Bach trung kinh ghi lich tii nSm 1624 de'n nam 1799 (tdi tin r i n g ngay a'y dng cd cho ehep lai cud'n lieh nay de diing). Lich trong cud'n Bach trung kinh nay khac b i n lich Trung Qude. Nhd khao ciiu cud'n lieh nay, dng vidt bai Lich vd lich ddi Le dang tren Tap chi Khoa hgc va tren Thanh Nghi (6). Tdi tin r i n g hai bai nay la mdt. Trong bai nay, dng phat bieu nhiing y kie'n dau tien cua minh ve lich Viet Nam xUa khae lich Trung Qud'c, eu the la lich nha Le khac lich nha Thanh.
Cae tac pham ve" lich eua dng g i n day dUde tuyen vao bp sach La San Yen Ho Hodng Xudn Hdn (7).
Thud dd, tren cd sd khao sat ban ehep tay cud'n Bdch trung kinh, va doi chieu vdi sii sach, trong bai Lich ud lich ddi Le, dng da riit ra ma'y nhan dinh quan trpng:
R g h i ^ eijru JJch sit. s6 l O j P l l
"2a. "Lich ta va lich Tau cd khoang khae nhau. Khoang dai nha't la tii nam Thanh Thuan Tri nguyen nien [tiic Le Phuc Thai nam thii 2] (1644) de'n nam Gia Long thii 12 (1813); trong khoang 171 nam iy, hai lieh khae nhau lim".
2b. "Trong khoang ddi Tay Sdn lich dung la mdt thii lich gdn gidng (chiing tdi nha'n manh - LTL) lich nha Thanh".
2e. "Trong mdt nUdc ta cd liie diing de'n hai thii lich, nhU ddi Nguyin Tay Sdn d Bic va Trung va chiia Nguydn Phiic Anh d Ddng Nai" (8).
Dd la nhiing nh^n dinh chinh xae.
Nhung, diidng nhU bai bao dd chUa gay diidc sU chii f thich dang trong gidi nghien ciiu. Phai chang, do d dd ehi diia vao mdt ban lieh ehep tay chUa tiing tha'y mdt sach sii nao n h i c den, va lai liic dd dng cUng ehUa cdng bd toan bd lieh thdi Le ma dng khao sat dUdc. Thdm niia, khi a'y thdi cudc diy bien ddng: Cach mang thang Tam 1945, toan qud'c khang chie'n; sach vd that lae; sau dd khdng lau dng lai sang Phap.
Lau d i n it ngudi de y den phat hidn nay cua dng.
3. Chic hpc gia Hoang Xuan Han eung tha'y cud'n Bdch trung kinh ehep tay ehUa du siic thuyet phue, chUa du tin eay, nen v i n kien tri theo duoi cdng viee nay, nhUng theo mdt hUdng khac.
Ong da tien hanh khao ciiu lich s^ lich Trung Qud'c va nhan r a lich thdi Minh diing phep Dai Thdng, lich thdi Thanh diing phep Thdi Hien, dng dii doan rang d nude ta thdi Ld v i n diing phep Dai Thd'ng nen diing may tinh phue diing lich nay. Ket qua tinh toan eho tha'y, lieh Dai Thd'ng phue diing hoan toan gid'ng nhU lich trong Bdch trung kinh, lai trung vdi s^ lieu, v^y la dii doan tren cua dng la dung.
4. Nam 1982. Giao sii Hoang XuSn Han tdng kd't thanh qua nghien ciiu trong 38 nSm cua minh trong tac p h i m Lich vd lich Viet Nam (9) in tai Paris. Tac p h i m nay cung diide in lai trong tap I bd sach La Sdn:
Yen ho Hodng Xudn Hdn (10).
Ndi chung, ed the coi tac pham nay nhii mdt cud'n sach ehuyen khao va giao khoa ve Lich hpc va nhiing va'n dd" hdn quan, tuy chi cd hdn 100 trang, nhUng ndi dung rat phong phii. Song, ciing phai thtfa nhan ring: day la mpt cud'n sach ra't khd dpc, nha't la ddi vdi cae nha khoa hpe xa hdi. Bdi vi Lich hpc vd'n la mdt khoa hpe Hdn/da nganh; dpc nd can cd ca kie'n thijc khoa hoc tii nhien va khoa hpc xa hpi; vi ndi dung sach ra't rdng ma cd dpng, ed tri thiic nhieu tang, nhieu Idp, n i m dUdc mue trUde mdi dpc dUde muc sau, tii ngii chuyen mdn hd CO va nha't la d nude ta ra't thieu kidn thiic v^ Thien van hpe, bdi hang ehuc nam qua, trong chuong trinh pho thdng cua ta khdngj ed mdn hpe nay.
Trong sach, Giao sU da trinh bay ngia gpn ve" cic ddn vi thdi gian lich nhU nam, thang, ngay, gid; cae loai lich ed ban dUdc diing trong eac ndn van hoa khae nhau nhit lich Diidng, lich Am • DUdng phUdng Tay, lich Am - DUdng A Ddng, lieh Viet Nam.
5. Trong cud'n Lich vd Lich Viit Nam, khi trinh bay ve lich Am - DUdng A Ddng, dng da neu ro lich st£ lich Trung Qudc, qua do t a tha'y ngUdi Trung Qud'c dd tam ddn viec nghien eiiu va eai each lieh nhieu nha't, lieh Trung Qud'c phiic tap nha't. Chiing tdi mud'n nha'n manh ma'y nhan dinh sau ciia Hoang Xuan Han:
"5a. "TH Hoang Dd' dd'n T i n , ddi lich 6 lan. Han ddi 4 Ian. Tii Nguy de'n Tu^, ddi 15 l i n . Tuf DUdng de'n Ngu Dai, doi 15 lan.
Tii Kim d^n Nguyen ddi 5 lin".
tjoc g i i ^oang Xuan ^an... 25 5b. "Phdp lich Thu Thdi, dUde ban hanh
nam 1281... Khdng nhiing trong 97 nam ddi Nguydn khdng ddi phdp lich, ma trieu Minh iJlp tii nam 1368 cung ndi theo, chi ddi ten ra lieh Dai Thd'ng ... Phep lich eua Quach Thu Kinh (Thu Thdi - Dai Thd'ng) da dupe dung sudt trong 363 nam ma khdng dieu ehinh...". Nhu vay la Phep Dai Thd'ng diidc diing din ndm 1643, tiie la hdt trie'u Minh.
5c. "Nam 1644, d Trung Qude, trieu Thanh thay trid'u Minh, lidn dung phdp lich mdi cua ngiidi giao si Tay phUdng da de nghi tii ddi Minh". "La'y NhUdc Vpng (Adam Schall von Bell - giao si ngiidi Diic) eoi viee lich, lap lich mdi gpi Lieh Thdi Hie'n". "Phep a'y dupe dung sud't ddi Thanh"" (11).
Lieh nay diing phep tinh lUdng giac eau va cac sd lidu quan sat ciia thien van hpc phUdng Tay, nen chinh xae hdn.
6. Hoang Xuan Han cdn trinh bay tUdng doi day du vd" phep Dai Thd'ng. Dd la ed sd cho viec phuc tinh lich nay nhu da neu d muc 3.
7. Trong cud'n Lich ud Lich Viit Nam, khi viet ve lich Viet Nam, Hoang Xuan Han da tim trong sii lieu Viet Nam cac thang nhuan (va mdt vai ngay sde tha'y khac lieh Trung Qudc) dem ddi chieu vdi cac thang nhuan trong lieh Trung Qud'c, lap thanh bang thang nhuan va riit ra nhan dinh:
"7a. 'Tii ddi Dinh ddn he't ddi Ly Thai Tdng, cae vua Viet dung lich hang nam vua Td'ngca'p cho".
7b. "Vdi eac sii t h i n qua Tdng, Mai Nguyen Thanh (1057), Kig"u Van Tii, Mai Canh Tien, Ly Ke Tien (1062), Quach Si An, Dao Siing Nguyen (1069), ed the ed phiidng tien hoc phdp lich cua Tdng". Ta tha'y nam 1080 la l i n d i u tien ta ed thang nhuan khae lich Trung Qud'c. Nam 1300 la nam eudi ciing lich ta cd nhuan khac lich Trung Qudc. Trong khoang 1080-1300, cudi
Ly, d i u Tran, lich 2 niidc khae ban nhau.
"Duyen cd ed sii khac nhau la bdi d trieu Ly da cd ty tinh lich theo mdt phep tuy eua Td'ng nhung Td'ng da bd. Hoac lich gia trid"u Ly khdng biet sii a'y, hoac cd bid't nhiing khdng dii tin tiic de dd'i theo".
7e. "Ne'u mud'n hoc phep lieh Thu Thdi, eiing phai tim each hpc trdm". Nam 1301, sii than "Dang Nhii Lam ve trdm ban do cung Uyen, mua da'u ban do, sdch cdm".
'Tdi nghi r i n g ehinh trong dip nay, ngUdi niidc ta hpc dupe phep lieh Thu Thdi ...
Bang thang nhuan tren cho hay r i n g 4 nam sau (1306), nam Binh Ngp cd thang Gieng nhuan ca trong 2 lich Tran va Nguyen. Cho den cuoi ddi Minh (1643), Cling khdng tha'y da'u hieu gi td sii hai lieh Viet va Trung khac nhau niia".
7d. "Ddi Thanh bd phep lich Dai Thd'ng.
Ly luan ddn gian nha't la Vidt lieh tie'p tue theo phep eu trong khi Thanh Hch theo phep mdi, eho nen eo sii so le giiia nhiing thang nhuan. Phep cu la phep Dai Thd'ng. Vay ne'u ta tim lai diide phdp Dai Thdng ... thi ta ed the tai lap lai toan lich ddi Le" (12).
'Trii Tay Sdn, chic chin nude ta khdng theo lieh Thanh trUdc nam 1813". "Bach trung kinh dich thiie ehep sdc va nhuan lieh Viet, va lich Viet trong thdi ky nay (1644-1812) dieh thiic theo phep Dai Thd'ng" (13), vay, khac b i n lieh nha Thanh.
Nhii vay, theo dng, nha Le trung hiing, chua Nguyin d xii Ddng trong, ddu thdi Nguyen deu dung phep lich Dgi Thong vd khdc lich Thanh.
7d. Nam 1810, Nguydn HCu Than di sU sang Thanh, mang bd sach Lich tiidng khao thanh day phep lam lich ve, tau vdi vua r i n g : "Vang lenh trdi ma trao thdi tie't eho dan la viee lam dau khi diing nude. Lieh Van Toan niide ta... dung phep lich Dai Thd'ng, hdn 300 nam ehua he sita ddi. Gang
2& Rghien cthi Lich sir, so l O g g l J lau lich cang sai. Khoang ddi Khang Hi,
mdi tham khao phep lieh Tay Dudng ma bien thanh sach nay, ve" phan do dae tinh toan, thi sach nay tinh tudng, so vdi phep lich Dai Thdng, mat xac hdn. Va lai cd dung cae phep Tam tuye'n bat giac (Liidng giac - trigonometrie) ra't la dieu. Xin giao sach nay eho Kham thidn giam giam lenh va thien van sinh de khao hoc phep nay. NhU vay thi dp trdi mdi diing, tiet hau mdi chinh" (14). 6 n g viet: 'Tii 1813, lieh tridu Nguyin (lich Hiep Ky) theo phep lich Thdi Hien (eua nha Thanh) " (15), nen ra't gid'ng lich nha Thanh.
7e. "Hp Nguyen, tii ddi lam chiia Dang Trong cho den ddi lam vua Viet Nam thd'ng nha't, da theo lich nha Le va v i n giQ nien hidu nha Ld. Nhung trong thiic td', sau khi Nguyin Phiic Nguyen tuyet giao vdi Trinh Trang (1627), chic chin chiia Dang trong phai tii dat ngudi soan lieh" (16). Dieu phdng doan eua Hoang Xuan Han la diing, bdi khi khao ciiu Kham dinh van nidn thu, tdi tha'y sach nay in 171 nam lich eua ehiia Nguyen d xii Dang trong tU 1631 den 1801.
7g. "Ve phdp lieh ddi Tay Sdn (1789- 1801), tdi khdng cd nhiing tU lieu ddi a'y mang tinh lich de quyet doan a'y la phep, Dai Thd'ng hay phep Thu Thdi. NhUng theo Bdch triing kinh, thi hinh nhii (chiing tdi nha'n manh - LTL) tii trieu Quang Trung, Bac trieu T&y Sdn theo lich nhd Thanh""
(17). Nhan dinh nay khdng b i n la ldi k h i n g dinh, Hoang Xuan Han than trpng diing til
"hinh nhii' va nhU vay la cd khac vdi nhan dinh 2b eua dng vao nam 1944, liic dd Hoang Xuan Han cho la hai lich gdn gid'ng nhau. 0 diidi, tdi se binh luan chuyen nay.
8. Theo cac nhan dinh tren, Giao sU Hoang Xuan Han da cho in cac lich trong cud'n Lich vd lich Viet Nam, gdm:
8a. Lich Le (Kham Thu), tii 1644 de'n 1788 (Lich phuc tinh).
8b. Lieh Tay Sdn (Thdi Hidn), tii 1789 den 1802, theo lieh Trung Qude.
8e. Lich Van Tuyen (chiia va vua Nguyin), tit 1780 ddn 1812 (Lieh phuc tinh).
8d. Lieh Hiep Ky (nha Nguyin va tiep theo), tif 1813 ddn 1999, theo lich Trung Qudc (18).
Nhii v^y la, Hoang Xuan Han khdng cdng bd p h i n lieh Dai Thd'ng do dng tinh tii nam 1428 den nam 1643.
9. Trong cud'n Lich vd Lich Viet Nam, Hoang Xuan Han edn phe binh cudn Bdng dd'i chieu Am Diidng lich 2000 ndm vd nien bieu lich sii! (19) ciia Nguydn Trpng Binh, Nguyin Linh va Biii Viet Nghi, gdm 6 y- sau:
"9a. "Dd chi la bang lich Trung Qud'c".
9b. "Cac tac gia khdng cho biet hoac phep tinh hoac ngudn gdc cOia nhiing sd kidn". "Cac tac gia ... vd'n biet tU lieu Bach triing kinh". 'Tdi hdi r i n g ban Bach triing kinh ma eac tae gia mach, nd khae ban tdi da diing chSng?".
9e. "Cae tac gia khdng biet ... cac thang nhuan (trong stt Viet) khdng tha'y trong lich Trung Qud'c. The ma hinh nhU cac tac gia khdng biet sii a'y (lich Viet, trong Bach triing kinh khac lich Trung Qud'c)".
9d. "Cae tae gia trinh thdm bang Am lich Viet Nam tinh theo miii gid 7... i t phai tinh lai hoan toan ... Cd lam nhU vay khdng?".
9d. Ve hinh thiic "sd' kien ... de tinh so Can Chi cua ngay, thi, vdi sd' kien ddc nha't d dau nam, nen phai tinh kha ldi thdi".
9e. "Cac tae gia danh rieng mdt d thudng xuydn diing 5 tin hidu ... Nhung quan niem ddi vdi hai sd' ST va gh khdng ddn gian, ro rang, cho ndn khdng trd phep Igip a'y mdt each nhat dinh. Ket qua la d^t nhieu ca
Ijoe gi^ ^ a n g Xuan Ijan..
ngoai le khd giai thieh, va each dung trd nen phiic tap, te toai, nen khd hieu va khd nhd, trai vdi muc dich eua nhflng loai bang nay.
Tdi e r i n g nhGng dpc gia khdng quen vdi ldi phSn tich toan hpe, de'n nan ehi va khdng ldi dung het kha nang eua bang nay" (20).
10. Tdi xin binh luan ngay ve 4 y d i u (9a den 9d) eua Hoang Xuan Han. TrUdc tien phai ndi r i n g , nhiing y kie'n cua Hoang Xuan Han la ra't sau sic. Chiing ta ed the tha'y: Tae gia dich thiic ciia sach Bdng dot chieu Am Diidng lich 2000 ndm vd niin bieu lich sit ehi la dng Nguyen Trpng Binh.
Ong khdng biet de'n cudn Bdch triing kinh, nen khdng liet ke chiing vao muc Tdi lieu dan b cuoi sach; bdi the ta't nhien lieh dUde soan "chi la bang lieh Trung Qud'c" nhu nhan dinh 9a cua Hoang Xuan Han. Nhu vay, tra ldi cau hdi d 9b la: "ngudn gd'c nhiing sd' kien" thiic sii la'y tii cac cud'n lich cua Trung Qud'c, chang lien quan gi de'n cac cud'n Bdch trung kinh. Ong Nguyen Trpng Binh khdng phai sii gia nen khdng biet cd nhiing thang nhuan trong cac cud'n co sti Viet khdng cd trong lieh Trung Qud'c diing nhu nhan dinh 9e eiia Hoang Xuan Han.
Khi sach b i t d i u diide in, dng Nguyin Trpng Binh da ma't, dng Nguyen Linh viet LM noi ddu tuy cd nhac de'n cud'n Bdch trung kinh, nhiing that ra dng Nguyen Linh khdng khao eiiu ky nen khdng biet lich Viet Nam khac lich Trung Qud'c d nhiing chd nao va ne'u cd biet thi eiing khdng biet lam the' nao de the hien vao trong ndi dung cud'n lich nay. Cdn dng Hoang Xuan Han cd eau hdi 9d la do dng Nguyen Trpng Binh khdng gidi thieu ro cac so' lieu ciia lieh eCta 35 nam eudi the' ky 20 la'y tif Lich thi'ky XX (21) ma Hoang Xuan Han khdng ed trong tay nen khdng biet, d niidc ta, Nha Khi tiidng da soan cudn nay theo mui gid 7.
Ldi phe binh eua Hoang Xuan Han d diem 9d va 9e la diing, ehinh dieu nay da
"mach bao" tdi, hay soan mdt cud'n Lich Viet Nam, theo mdt hinh thiie mdi de khic phuc 2 nhiipc diem nay, cdn npi dung phan hch Viet Nam xUa thi dung lich do Hoang Xuan Han phue tinh.
11. Nam 1985, tdi dupe dpe bdn in cud'n Bdch triing kinh (BTK), cd lich Le tii nam 1624 de'n nam 1785. Ve thdi lUdng, ban in nay it hdn ban ehep tay ma Hoang Xuan Han diide dpc 14 nam.
Nam 1994, tdi lai dupe dpe bdn in cud'n Khdm dinh vgn nien thit (VNT) ed lich Le trung hiing tii nam 1544 de'n nam 1630, lich chiia Nguyen d xii Dang trong tii nam 1631 de'n nam 1801 va lich nha Nguyen tii nam 1802 den 1903, gdm 360 nam. Cud'n VNT qiiy hdn cud'n BTK, bdi lich trong VNT sdm hdn trong BTK 80 nam va keo dai ve sau them 118 nam; dac biet d khoang giiia, tir nam 1631 de'n 1801, lieh trong 2 cud'n nay khdng triing nhau, bdi d doan dd cud'n VNT chuyen sang ghi lich xii Dang trong.
Hai tit lieu tren Id nhiing bang chiing khong the bdc bo diidc ve sU ton tgi ciia lich CO Viet Nam, khdc hdn lich Trung Qudc.
Nam 1987, tdi bat d i u khao cifu ban chip tay cud'n Lich dgi niin ky bdch trdng kinh (LDNK) (22), gdm lich 144 nam- tii 1740 de'n 1883, mdt giai doan day nhiing bie'n ddng trong lich sii niidc ta. Sach ehep lich Le trung hiing tic nam 1740 de'n nam 1788, lich Tay Sdn tit nam 1789 de'n nam 1801, lich theo phep Dai Thd'ng tii nam 1802 de'n nam 1812, lich nha Nguyin tii nam 1813 den nam 1883. Vi ehep lich nhiing thdi dai da qua, nen la lich da dupe dung 6 diidng thdi. vay ra't quy. Hiem mdt ndi, sach bi ehep au, sai sdt nhieu, nhUng da phan la sai sdt ngiu nhien, cd the siia dupe. Cud'n lich ehep tay nay cd khoang 80
Rghien ciJru Ljeh sir. s6 lO-gglJ ldi, tdi da van dung dinh tinh ly thuyet ma
sifa sai dd hieu dinh dupe g i n hdt cae ldi, ngoai trir 2 ldi sai mdt each he thd'ng do ehep n h i m tit lich cua nam khac. Sau khi hieu dinh cudn LDNK, tdi thdy phdn lich cua nhiing ndm con cd trong hai cudn lich diiac in kia deu triing vdi cud'n LDNK. Dieu dd ehiing td viee hieu dinh dang tin cay.
Cdi quy cda cud'n LDNK chinh Id dogn lich Tdy Sdn, vi de'n nay ta biet ditdc chi con sdch ndy ehep lich dd. Ngoai ra nd cdn cho ta bie't chinh xac lich ba nam (Binh Thin - 1856, Binh Din - 1866, Ky Ti - 1869) d thdi Tu Diic ma lich d cud'n Khdm dinh van niin thii chi la lieh dii soan, khdng dUde diing d dUdng thdi, nen phai theo lich d cud'n Lich dgi niin ky bdch triing kinh nay mdi dUng.
Tdi dang chuan bi de cd the edng bd' toan van va kdt qua khao citu cud'n Lich dgi nien ky bdch trdng kinh nay trong mdt dip g i n day. Cd mdt dac didm la cac cud'n Bdch trung kinh (nhu cud'n lich ehep tay ma Hoang Xuan Han da dpe, eiing nhU ban in BTK va ban ehep tay LDNK ma tdi dpc) chi tap hdp lich cac nam da qua, nen lich trong dd la lieh dUpc diang d diidng thdi; trong khi dd cae cud'n Vgn niin thii (hoac Vgn nien lich) nhu cudn VNT (ma tdi dUdc dpc va cud'n Hodng trieu Minh Minh ugn niin thii ma Td lieh cua Nha Khi tupng ditde dpc tnidc nam 1968) thudng cd 2 phin; phan trudc nam soan va in la lich diidc dung d dUdng thdi; p h i n sau la lich dii soan, vd nguyen t i e , Jich mdi nam trUdc khi ban bd mdt nam cdn dUdc kiem tra lai va cd the ed sita chiia nen chua chic da la lieh dUde dung d ditdng thdi.
12. Vay nen dUdi day tdi xin trinh bay cac ket qua nghien cilu cua minh nhu mdt bing chitng k h i n g dinh nhiing luan doan khoa hpc cua Giao sU Hoang Xuan Han ma tdi da d i n lai d didm 2 va 7 va bd sung thdm eho dUpc hoan chinh.
a) Giai dogn 1080-1300: Nhd bang thang nhuan lap ra tit cd sii, Hoang Xuan Han nhan dinh khoang thdi gian nay, dUdi thdi Ly va thdi T r i n lich 2 niidc khac b i n nhau.
Liic diu, lich khac nhau la do sit t h i n cua ta da hpc dUdc phep lam lich cu cua Tdng, theo dd ta soan la'y lich rieng; nhUng khi dd Tdng da dd'i phdp lich, diing phep mdi. Dieu nay cd ly, nhung de'n nay ta chUa tim thSfy lich Viet Nam va eiing chiia phuc tinh dUde lich ciia giai doan nay; nhung ed thd theo each lam eua dng ma phuc tinh. Cudi cung, lich ta soan lai gid'ng lieh Td'ng bdi nam 1301, sir t h i n Dang Nhii Lam sang Td'ng la'y diide phdp lich mdi. Sau nay con dng la Dang Ld trd t h a n h lieh quan d i u tien dUdc ghi ten trong sxi sach.
b) Giai dogn 1301-1643: Theo nhan dinh 5b, thi giai doan nay 2 niidc deu theo phep lich Dai Thd'ng, ma bang thang nhu^n Hoang Xuan Han lap khdng tha'y mdt thang nhuan nao khae nhau, nen dng cho r i n g giai doan nay hai lich gid'ng nhau. Tuy vay, theo ket qua khao citu ciia tdi tit cud'n Khdm dinh ugn nien thii, thi tii 1544 den 1643 lieh 2 nUde v i n khac nhau chiit it, tuy eung phep lich, bdi phep x i p xi bac ba r i t nhay, thdng sd hdi khac nhau mot chiit, kdt qua tinh ra se cd sii khae nhau chiit it.
Tham ehi nam Tan Dau (1621) lieh 2 nUdc edn khae nhau thang nhuan, dd la mdt sii khac nhau Idn; lich ta nhuan thang Ba, lich Trung Qud'c nhuan thang Hai (23). NhU vay ta ed thd phan doan r i n g , sud't ea giai doan nay ta v i n soan la'y mdt lich ridng;
tuy lich 2 nude cung theo phep Dai Thdng nhUng v i n khae nhau, tuy khdng nhieu; chi tide la den nay chiing ta chUa tim tha'y lich Viet Nam eho giai doan nay.
c) Giai dogn 1644-1788: Ngay tit nam 1944, Giao su Hoang Xuan Han da cho r i n g giai doan nay lich 2 niidc khac nhau nhu d nhan dinh 2a. Nam 1982 c6 them
^9C giA Ijoang Xuan Ijan...
nhan dinh 5b vd sii thay ddi lich phap d Trung Qud'c, va tha'y lich trong ban ehep tay cud'n Bdch triing kinh trung vdi bang thang nhuan, triing vdi lieh phuc tinh theo phep Dai Thdng, dng di de'n kdt luan: nhd Thanh diing phep lich Thdi Hie'n, nhd Le ddng phep lich Dgi Thong, lich cua 2 niidc khdc hdn nhau, nhu d nhan dinh 7d. Hoang Xuan Han da cdng bd lich phuc tinh nay trong Lich vd lich Viet Nam. Cae nha khoa hpc xa hdi trong va ngoai nUde deu tin va d^ng lich Dai Thdng do dng phuc tinh. Tuy vay, Giao sii Nguyin Xien ehua thGa nhan dieu nay. Cudi cung, toi tim tha'y lich nay trong ca ba cud'n lich co: Bdch trung kinh (ban in), Khdm dinh ugn niin thii (ban in) va Lich dgi niin ky bach trung kinh (ban ehep tay). Didu nay da k h i n g dinh sii diing dan CLia cae luan doan va phUdng phap nghien ciiu cua Hoang Xuan Han.
d) Giai dogn 1789-1801: Nam 1944, theo cudn Bdch trung kinh ehep tay, dng cd nhan dinh 2b: "Trong khodng ddi Nguyen Tdy Sdn lich ddng la mdt thd lich gdn giong lich nhd Thanh". Nhitng rdi dng khdng tim dupe SLf lieu ve sii khae nhau gifla lich Tay Sdn va lich Thanh, Hoang Xuan Han eung khdng tim ra b i n g chitng r i n g lieh Tay Sdn theo phep lich nao. Trong khi ca hai didu tren dng da lam dupe ddi vdi lieh Le trung hiing, nhii da neu d nhan dinh 12c. Vdi mdt thai dp than trpng, nam 1982, dng da thay doi y kie'n mdt chiit cho rang lich Tay Sdn la lich Thanh nhiing dng than trpng dung ehii "hinh nhii" vdi nhan dinh 7g: "Hinh nhii tii trieu Quang Trung Bac trieu Tdy Sdn theo lich nhd Thanh".
Nhiing, theo ket qua khao ciiu ciia tdi tit cudn Lich dai nien ky bdch trung kinh thi tha'y, qua that lieh Tay Sdn "gdn giong lich nhd Thanh" nhu nhan dinh 2b sau khi Hoang Xuan Han dpc ban ehep tay cud'n Bdch trdng kinh vao nam 1944. NhU vay,
ca hai cud'n lich ehep tay (cud'n Bdch triing kinh ma Hoang Xuan Han dpc nam 1944 va cudn Lich dgi niin ky bdch trung kinh deu eho thay: lich Tdy Scfn co khdc lich Thanh mgt it (co 3 ngdy sdc khdc nhau), vd khdc hdn lich chda Nguyin (ve 3 thdng nhudn).
Tdi da trinh bay dieu tran trd nay eua Hoang Xuan Han trong Hdi nghi khao cd hpc nam 2002 (24).
e) Giai dogn 1802-1812: Tuy Bdch trung kinh ehep tay khdng cd lich nhiing nam nay, nhung vdi sii lieu d bang thang nhuan ma Hoang Xuan Han lap; sau khi phuc tinh lich Dai Thd'ng, tha'y lieh nay triing vdi sii lieu; Hoang Xuan Han da cho r i n g lieh Dai Thd'ng diidc dung cho de'n nam 1812 nhU nhan dinh 7d, dng cdng bd' lich Dai Thd'ng phuc tinh trong cud'n Lich vd lich Viet Nam.
Giai doan nay cd 2 lieh khac nhau trong 2 cud'n lieh ed. Mgt la: Ban ehep tay Lich dai niin ky bdch trung kinh eho mdt lich trung vdi lich Dai Thd'ng phuc tinh ciia Hoang Xuan Han. Cd bing chiing r i n g Phan Thiie Triic da dung lieh nay de viet Qudc svt di biin (25). Hai Id: Trong khi dd ban in Khdm dinh vgn niin thii cho mpt lich khac ma Bgi Nam thiic luc (26) dung.
Hai lich nay khae nhau d 3 ngay sde, day chi la khae nhau nhd. Tat nhien lich trong VNT la lich chinh thite dupe dung d dUdng thdi vi nd ed tinh lich sii va phap dinh, dxtdc Kham thien giam soan va khic in. dupe Qudc sd quan diing. Lieh trong LDNK cd tinh khoa hpc cao hdn, bdi nd dupe kiem chiing nhd viec tinh toan ciia Hoang Xuan Han b i n g may tinh hien dai. Ra't cd the lich nay do Tu thien giam nha Le soan s i n cho eac nam ve sau, khi nha Le da eao chung, nd khdng cdn tinh phap dinh niia, nhUng v i n edn nhiing ban diide lUu giii d ngoai Bie thanh va do khdng biet rd dieu dd nen Phan Thiic Triic da dung nham.
30 Rghien ciJru Lieh sir. agjOgOl*
f) Lich chua Nguyen Ddng Trong: Ngay tii nam 1944, qua sOt lidu, Hoang Xuan Han da eho r i n g thdi Tay Sdn, ehiia Nguyin cd mdt lieh rieng, nhii nhan dinh 2e. Sau khi phue tinh lich Dai Thong vao nam 1982, tha'y triing vdi bang thang nhuan, Hoang Xuan Han da cdng bd' lich chiia Nguyin tif nam 1780 de'n nam 1801 trong Lich ud lich Viit Nam.
Theo ket qua khao citu cud'n Khdm dinh vgn nien thit, thi ehiia Nguyin ed lich ridng tir nam 1631 de'n nam 1801, ludn khae lieh Trung Qud'c, liic dau khac lich Le trung hung nhieu, ve sau sii khac nhau giam dan, nhung khae h i n lich Tay Sdn. Lieh khoang 1780-1801 trong sach nay triing vdi lich hoang Xuan Han phue tinh.
13. Mpt vai khao citu khac cd lien quan de'n lich.
a) Hoang Xuan Han lam mpt loat cac bang va bieu dd de ddi nam Cdng lich, Phat lich va Can Chi cdng bd' tren bao Khoa hgc xUa, sau dang tren Tap san Sd-Bia, rdi in lai trong Lich vd lich Viet Nam. Phat huy y tudng cua dng, tdi dung toan dong du lam ra mdt loat lich vinh e6u cho lich Can Chi (nam, thang, ngay, gid); Nhi thap bat tii (nam, thang, ngay); lap 64 trung quai theo Mai hoa dich so'vk theo Thieu Vi Hoa; tim huyet md theo Linh quy bat phap trong Thdi cham da cdng bd' tren cae tap chi chuyen nganh, sau dd in mdt p h i n trong cud'n Lich hai the'ky (1802-2010) vd cdc lich vinh cdu (27) eiing nhii trong cud'n Vietnamese old-time calendars. Perpetual calendars of stems and branches.
Chronoacupuncture (Acupuncture on the optimal time-interual) (28) va se he thd'ng boa lai de tie'p tue edng bd'.
b) Trong bao Khoa hgc tit nam 1942, Hoang Xuan Han da viet bai Co Kieu bi bat, rdi nam 1943 lai viet Cdu chuyen "Co Kieu bi bdt" la'y tit tit cau sau trong Truyen Kieu:
"Dim thu gid lot song ddo Mgt viing trang khuydt, ba sao giiia trdi .
c) Nam 1984, nhan Tet At SL(U s i p tdi, Tet Viet Nam de'n trudc Tdt Trung Qudc 1 thang, nhidu nha lam lich trong nUdc da tham gia giai thich, nhUng chUa ditdc thuydt phuc lim, vi ngudi vidt khdng tam ly (dang ra cin giai thich vd viec khae nhau giiia 2 lieh lai bai bac lieh Am) lai dimg tit ngii khdng c h u i n xac (nhii dang le nen diing tit
"trUdc" va cum tif "lich Trung Qud'c"; lai diing tir "sdm" va cum tif "lich eii").
Hudng iEng viee tuyen truyen d trong nUdc, Hoang Xuan Han da vie't bai Nam At SOu cdm tinh con trdu hai ddu? (29) tren bao Bodn Kit, lam cho ddng bao n i m dUdc tinh khoa hpe cua lich Viet Nam n h i m bac lai nhiing luan dieu phan tuyen truyen. Ong tinh "ngay Tet" Am lich (ngay sdc d i u tien ciia nam At Siiu) cho 4 dia diem tren the gidi va chi ra: d Washington vao ngay 20-1-1985;
d Hd Ngi vdo ngdy 21-1-1985; d Paris vao ngay 19-2-1985; 6 Bac Kinh vdo ngdy 20-2- 1985. Vay la, vdi eac miii gid khae nhau, Tet Am lieh se rdi vao nhiing ngay khae nhau, lech nhau hoac 1 ngay, hoac 1 thang. Hoang Xuan Han trinh bay mdt each ddn gian va rd rang, lai dung tii ngii ehinh xac, nen rit thuye't phuc hdn nhieu cac bai do cac nha lam lich trong nUde viet.
14. De kdt lai, tdi mud'n riit ra mot vai phitdng phap nghien citu cua Giao sU Hoang Xuan Han ma tdi linh hdi dUdc trong qua trinh nghien ciiu lich.
Thd nhdt: Hoang Xuan Han ra't eoi trpng eac t u lieu gd'e, co. Vao nhiing nam 40 cua the ky XX, cai thdi ehua may ai de y den gia tri ciia nhiing tit heu cd, nhiing van ban gd'c, dng da siiu t i m dUde nhieu t a lieu quy trUde khi ehiing bi buy hoai trong chidn tranh va cae bie'n co xa hdi, khi thi mua, khi thi mUdn ngUdi ehep, khi thi cho rap cac van bia quy.
Ijoc gii Ijoang Xuan ^an.. 31 khi thi chyp lai cac sac phong... de chuin bi
eho mdt cudc nghien cifu lau dai.
Tha hai: Giam dinh van ban. Day la edng viec quan trpng d6 bidt thi phi, ehan gia, gia tri dich thiic cua tifng van ban. De lam viec nay, chang han nhii ddi vdi ban ehep tay cud'n Bdch trung kinh, vd'n ehUa du dp tin eay; Hoang Xuan Han da lap bang thdng ke cac thang nhuan tit sii lieu de ddi chifng, diing may tinh phue diing lai lich theo phep Dai Thd'ng dd so sanh. Nhd vay khi ke't lu^n ban ehep tay Bdeh trung kinh chinh la lich nha Le trung hung thi that chac ehan.
Thd ba: Khao dinh van ban. Cdng viec nay ra't da dang, phong phii. Hoang Xuan Han thiidng van dung Ngdn ngii hpe. Hpc theo tinh t h i n dd tdi da van dung dinh tinh nguydn ly cua ma svfa sai phat hien va dinh chinh dUdc eac sai sdt in i n va ehep d 3 cud'n lieh cd.
Thd tit: Phuc diing. Hoang Xuan Han da lap luan dd each xac dinh lich Viet Nam giai doan nha Le trung hung dung phep lich Dai Thd'ng, dng tim thuat toan va phue CHU THICH
(1) Hoang Xuan Han: Lich vd lich Viet Nam.
Phu trUdng Tap san Khoa hgc xd hpi. Paris, 1982.
(2) H o i n g X u i n Han: Lich vd lich d(H Li, Tap chi Thanh Nghi, so 52, 53, 54 n i m 1944. Day la so d i e biet Tet Giap Than, t h i n g 1-1944, g6m ca 4 so tit 51 den 54, tr 43-48, 57.
(3) Bdch trung kinh, ky hieu A 2873. Thu vi&n Vi^n Nghien ciiu Han Nom.
(4) Khdm dinh van nien thU, ky hieu R 2200.
Thu vifin Quo'c gia.
(5) Le T h a n h Lan: Ndm trdm ndm lich Viet Nam (1544-2043), Nxb. Ha N6i, 2010.
(6) Xem ghi chii (2).
(7), (10). H o i n g X u i n Han: La Sm Yen Ho Hodng Xudn Hdn. Nxb. Giao due, H i Noi, 1998.
tinh lieh nay eho cae nam tif 1428 den 1812 va cdng bd' lich giai doan 1644 den 1812 mdt each chinh xac. Gid ddy, chiing ta cung ed the theo phiidng phap nay de phuc diing lich Viet Nam giai doan 1080 den 1300 ma theo dng lieh ta khac han lieh Trung Qude.
Lieh cd Viet Nam la hien hiiu eua mdt sii that lich sii. Vide tim lai nd dap ifng nhu cau ve' tinh chinh xae eiia ban than Sii hpc. Sii tdn tai eiia nd la net dep van hoa - lich sit ciia dan tdc. Nd thd hien mdt tinh t h i n ddc lap, tii eUdng cua dng eha ta, the hien mdt trinh dp nhat dinh ve khoa hpc eua td tien ta.
Gid day chiing ta da tim lai dUdc lieh ed Viet Nam tif nam 1544 trd lai day, trong dd cd 171 nam tii 1631 de'n 1801 cd 2 lich song hanh. Cdng dau la thupc ve Giao sU Hoang Xuan Han. Gid day, neu nhu ed mdt chiidng trinh lam viec nghiem tiie, dai hdi vdi sii diu tu thich dang va di theo ca hai hiidng la phue tinh va suu t i m cac cud'n lieh cd eua dng, chiing ta van cdn hy vpng tim dupe lich ed niidc ta d nhiing giai doan khac va nha't la giai doan 220 nam tii 1080 de'n 1300 ma dng da chi ra r i n g rat khac lich Trung Qudc.
(8). Ba nhan dinh nay trong Hoang Xuan Han:
Lich vd lich ddi Le, Tap chi Thanh Nghi, so 52, 53, 54 n i m 1944.
(9). Xem Hoang Xuan Han: Lich vd lich ddi Le, Tap chi Thanh Nghi, so 52, 53. 54 n i m 1944.
(11), Ba n h a n dinh nay trong Hoang Xuan Han: La Sdn Yen Hd Hodng Xudn Hdn, Nxb. Giao due, Ha Noi. 1998 (cu the: 5a • tr. 907, 5b - tr. 913- 914. 5c - tr. 939-940).
(12). Hoing Xuan Han; La San Yen Ho Hodng Xudn Hdn. Nxb. Giao due, Ha Noi. 1998. eu the: 7a d tr. 930, 7b 6 tr. 930-934, 7c 6 tr. 935, 7d 6 tr. 940.
(13), (14), (15), (16), (17), (18), (20). Hoang Xuan Han: La Son Yen Ho Hodng Xudn Hdn, sdd, tr. 943, 944-945, 943, 943, 949, 963-982. 953-954.
(Xem tie'p trang 74)
Rghien eijru Licli sit. s o J O j Q l i
tid'n quan trgng ve van minh dai hgc ciia ndn giao due dai hge mien Nam Viet Nam lue bay gid. Tuy nhien, do hoan canh chid'n tranh va keo theo la sfl bat dn xa hgi da lam gidi chinh quydn va gidi quan ly dai hgc khong tim dUde tid'ng ndi ehung trong ed ehe' tfl tri dai hgc.
Trong khi di tim mgt cd chd' hdp ly cho che do tfl tri dai hgc d mien Nam Viet Nam thi da phdn cac nha khoa hgc, gidi giao sU va ea he thdng chfnh quyd'n ddu tam cha'p nh&n y kie'n
CHU THICH
(1). Trung tam Lifu trQ Quoc gia (TTLTQG) II;
ph6ng De nhi cong hoa (DIICH); so 3549, (2), (3), TTLTQG H; phong DIICH; so 3549; tr. 32.
(4). Tran Quang DS; Tkp san nghien cilu h a n h chinh, so'3-1971.
(5). TTLTQG II; DIICH; so 3549; tr. 37.
(6). TTLTQG II; DNCH; so 3549.
eiia Giao sU Tdn Tha't Thidn: *^ai hge khdng phai la ndi tuydn truyen, dan ap, pha hoai, ^ ba't cha'p luat phap va quydn ldi ehung eua xfl sd. Dai hgc khdng phai la ndi chuyen de da'u tranh chinh tri. Dai hgc khong the thay the chinh trfldng va qude hgi. Dai hgc la ndi hgc d ca'p "dai", nghia la ca'p sang tao tfl tfldng trong tinh thdn vd tu xay dflng de ddng gop vao cdng cugc eai tie'n va canh tan xfl sd va xahgi" (11).
(7). Phu Thu tuang VNCH; so 30473; tr, 20.
(8). W T L s o 2 4 4 3 ; t r 45
(9), Phong v a n giao due dai hoc, P h a t trien xa hpi, so 4 nam 1972, tr. 184.
(10). TTLTQG II, Phong De nhi cong hoa; so 3548.
(11). T6n T h a t Thien; "Van de tu tri" T a tuiifng, so 8, 1970, tr. 137.
HOC GIA HOAI\G XIJAIV UAN
(19). Nguyin Trong Binh, Nguyin Linh va BiJi Viet Nghi: Bdng doi chieu Am Duang lich 2000 ndm vd nien bieu lich sii, Nxb. Khoa hoc xa hoi, Uk Noi, 1976,
(21). Nha khi tUdng Viet Nam: Lich the'ky XX, Nxb. Pho thong, 1967
(22). Lich dai nien ky bdch triing kinh, ky hieu A 1237, Thu vien Vien Nghien cilu Han Nom.
(23). Le Thanh Lan: Ddi chieu lich Duang udi lich Am-Ducfng cua Viet Nam ud Trung Quoc 2030 ndm (0001-2030) - Solar Calendar Comparison with Vietnamese and Chinese Lumsolar calendar 2030 years (0001-2030) - mWi^'^m 2030 if- (0001-2030) mmmmmmm, Nxb. Giao due, Ha Noi, 2007, tam ngu! (tr. 560).
(24). Le T h a n h Lan, TrSn Ngpc Dung: Gido sU Hodng Xuan Hdn noi ve lich Tdy S(Pi, trong cuon
(Tie'p theo trang 3J) NhUng phdt hien mdi ue khdo co hgc ndm 2002.
2003, tr. 780-782.
(25). P h a n Thuc Tnic: Quo'c sii di bien, Uy ban dich t h u a t phii quoc vu k h a n h dac t r a e h van hoa xua't ban, 1973.
(26) Quoc sii q u a n t r i e u N g u y e n ' Dai Nam nhdt thong chi, t a p IV, N x b . Khoa hpc xa hoi.
Ha Noi, 1971,
(27). Le Thanh Lan. Lich hai the'ky (1802-2010) vd cdc lich vinh cihi, Nxb. Thuan Hoa, Hue, 1985.
(28). Le Thanh Lan: Vietnamese old-time calendars. Perpetual calendars of stems and branches. Chronoacupuncture (Acupuncture on the optimal time-interual). Seacom Edition, Berlin 2003 (29) Hoang Xuan Han: Ndm At Sdu cdm tinh con trdu hai ddu? Bao Dodn Ke't (Paris), t h a n ? 9-
