Karlsson, Fred
Finnish: an essential grammar
Routledge, 1999
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Donaldson, Bruce
German: an essential grammar
Routledge, 2006
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Some grammatical errors made by the students of Unpam
 Artikel Jurnal
Kaplan, Jeffrey P.
English grammar : principles and facts
Prentice Hall International, 1995
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Poutsma, H.
Mood and tense of the English verb / H. Poutsma
P. Noordhoff, 1922
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