Randel, Jim, author
Facts on File Publications, 1986
Buku Teks
Keller, Gary, author
McGraw-Hill, 2010
Buku Teks
Remley, Jim, author
American Management Association, 2005
eBooks
Kau, James B., author
McGraw-Hill, 1985
Buku Teks
Shilling, James D., author
South-Western, 2002
Buku Teks