Bowman, Joel P.
Effective business correspondence
Harper & Row Publishers, 1979
Buku Referensi
Webster's guide to business correspondence
Merriam-Webster, Inc., 1988
Buku Teks
Murphy, Herta A.
Effective business communications
McGraw-Hill, 1991
Buku Teks
King, F.W
English business letters : commercial correspondence for foreign students/F.W. King, D. Ann Cree.
Longmans , 1979
Buku Teks
Merriam-Webster's guide to business correspondence : a merriam-webster
Merriam-Webster's, Incorporated, 1993
Buku Referensi