Gray, Loretta S.
Mastering idiomatic english
National Textbook Company, 1999
 Buku Teks
Samsiah Abdul Hamid
Mastering English for employment
Cengage Learning, 2012
 Buku Teks
Sambrook, G.A.
English language
Longmans, Green, 1947
 Buku Teks
Sambrook, G.A.
The English Language
Longmans Green & Co, 1947
 Buku Teks SO
Bennie, Michael
Glorier business library : mastering business english
Glorier International, 1999
 Buku Referensi