Ritz, George J., author
New York: McGraw-Hill, 1990
Buku Teks
Ritz, George J., author
McGraw-Hill, 1994
Buku Teks
Bank, John, author
Prentice-Hall, 2000
Buku Teks
Fandy Tjiptono, author
Andi Offset, 1996
Buku Teks
Hradesky, John L., author
McGraw-Hill, 1995
Buku Referensi