Swan, Michael
The new Cambridge English course. Student 4, Upper-intermediate
Cambridge University Press, 1993
Buku Teks
English for economics
Buku Teks
Brown, E.H. Phelps
A Course in applied Economics
Sir Isaac Pitman & Sons, 1953
Buku Teks
Low, Ona
Proficiency in english course
Edward Arnold, 1986
Buku Teks
Christhophersen, Paul
An english phonetics course
Longmans, Green, 1956
Buku Teks