Bovee, Courtland L., author
Pearson/Prentice Hall, 2007
Buku Teks
Madura, Jeff, author
South-Western College, 2001
Buku Teks
Twomey
South-Western Co, 1987
Buku Teks
Kinder, Peter D.
McGraw-Hill, 1988
Buku Teks
Soulsby, J., author
McGraw-Hill, 1995
Buku Teks