Robert, Collin
Comprehensive dictionary & thesaurus : French-English vol.1
Paris : Harper Collins Publisher, 2000
 Buku Referensi
English workshop
New York : Holt, Rinehart and Winston, 1995,
 Buku Teks
Holschuh, Louis W.
The functions of the English grammer/Louis W. Holscchuh
New York St. Martin's Press 1991,
 Buku Teks
Harahap, P.R.
English for banking/P. R. Harahap, editor khusus Harace H. Rice
Jakarta Praninta Aksara [date of publication not identified],
 Buku Teks
English grammatical structure : a general syllabus for teachers / L.G. Alexander...[et al.]
Longman Group UK Limited , 1975
 Buku Teks SO