Wichman, K.
McKay's modern German-English and English-German dictionary with rules as pronunciation
New York, David Mckay Company
 Buku Referensi
English workshop
New York : Holt, Rinehart and Winston, 1995,
 Buku Teks
Fowler, H.W. [Henry Watson], 1858-1933
A dictionary of modern English usage
New York Oxford University Press 1965
 Buku Referensi
Holschuh, Louis W.
The functions of the English grammer/Louis W. Holscchuh
New York St. Martin's Press 1991,
 Buku Teks
English grammatical structure : a general syllabus for teachers
by L.G. Alexander ... [and others]
Longman, 1975
 Buku Teks SO