English grammatical structure : a general syllabus for teachers / L.G. Alexander...[et al.]
Longman Group UK Limited , 1975
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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,
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Harahap, P.R.
English for banking/P. R. Harahap, editor khusus Harace H. Rice
Jakarta Praninta Aksara [date of publication not identified],
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Hughes, John
Times tenses and conditions/John Hughes and Tom McArthur
London Collins 1994,
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