edited by Charles D. Schewe
Haworth Press, 1991
Buku Teks
edited by Steven Spirn and David W. Benfer
Aspen Systems Corporation, 1982
Buku Teks
Ross, Austin, author
John Wiley & Sons, 1984
Buku Teks
edited by Donnie J. Self
Teagle & Little, 1977
Buku Teks
Kotler, Philip, author
Prentice-Hall, 1987
Buku Teks