Shapiro, Benson P., author
Richard D. Irwin, 1985
Buku Teks
Taffinder, Paul, author
Crest publishing, 1999
Buku Referensi
Bolt, Gordon, author
Crest publishing, 1999
Buku Referensi
Assael, Henry
Kent Publishing Company, 1984
Buku Teks
Stone, Bob
NTC Business Book, 1988
Buku Teks