REFERNCES
Arikunto, S. 2005. Manajemen Penelitian. Jakarta: PT. Asdi Mahasatya.
Azar, Betty Schrampfer. 2003. Fundamentals of English Grammar. Third Addition. USA: Longman Ltd.
Bungin, B. (2005). Metodologi Penelitian Sosial. Surabaya: Airlangga University Press
Corder, S.P. 1981. Error Analysis and Interlanguage. Great Britain: Oxford University Press.
Ellis, Rod. 1985. Understanding Second Language Acquisition. England: Oxford University Press.
Ellis, Rod. 1997. Understanding Second Language Acquisition. England: Oxford University Press.
Moloeng, Lexy J. 2006. Metodologi Penelitian Kualitatif. Bandung : PT Remaja Rosdakarya.
Pyle, Michael A. 2001. CliffsTestPrep TOEFL CBT. USA: IDG Books Worldwide, Inc.
Richards, Jack C. 1974. Error Analysis Perspectives on Second Language Acquisition. Longman Group.
Rhomdony, Deny. 2007. Integrated Comprehensive English Grammar. Jakarta:Visipro.
Sapir, Edward. 1949. Language: An Introduction to the Study of Speech. New York: Harcourt, Brace & World, Inc.
Sharpe, Pamela J. 2004. Barron’s How to Prepare for the TOEFL. 11th Edition. USA: Barron's Educational Series, Inc.
Sitanggang, Damianus P. 2008. The Ability of the 2007 Year Students of English
Literature Department, University of Sumatera Utara to Distinguish Present
Participle from Gerund.
Stilman, Anne. 1992. Grammatically Correct : The writer’s Essential Guide to
punctuation, spelling, style, usage and grammar. Ohio: Writer’s Bigest Books.
Surayin. 2003. Perfect English Grammar. Bandung: CV. Yrama Widya.
Susan M. Gass and Larry Selinker. 2008. Second Language Acquisition : An Introductory Course. New York. Taylor and Francis Group
Syamsudin and Vismaia Damaianti S. 2007. Metode Penelitian Pendidikan Bahasa. Bandung. PT. Remaja Rosdakarya
Thomson, A.J. and Martinet A.V. 1969. A Pratical English Grammar. Second Edition. England: Oxford University Press.
...: Maret 2013. Teaching Gerund to the Second Years Students of SMP N 3 Peusangan by Using the Five Finger Tehniques. Retrived from
http://kapabeujaya.wordpress.com/
...:Juli 2012 Definition of field research. Retrived from
http://www.businessdictionary.com/definition/field-research.html.
...: Juli 2013. Writing adding-endings-ed-ing-to-verb. Retrived from
http://usefulenglish.ru/writing/adding-endings-ed-ing-to-verbs.