King, F.W
English business letters : commercial correspondence for foreign students/F.W. King, D. Ann Cree.
Longmans , 1979
Buku Teks
Bowman, Joel P.
Effective business correspondence
Harper & Row Publishers, 1979
Buku Referensi
Aurner, Robert Ray
Manual for effective business correspondence / Robert Ray Aurner
South-Western Publishing Company, 1939
Buku Teks
Webster's guide to business correspondence
Merriam-Webster, Inc., 1988
Buku Teks
De Vries, Mary Ann
The Elements of correspondence
Macmillan, 1994
Buku Teks