Smykay, Edward W.
Macmillan Publishing Company, Inc., 1973
Buku Teks
George Allen and Unwin, 1972
Buku Teks
Martin, Andre J.
John Wiley & Sons, 1995
Buku Teks
James A. Tompkins, Dale A. Harmelink [editors]
McGraw-Hill, 1994
Buku Referensi
Gopal, Christopher, author
Business One Irwin, 1993
Buku Referensi