Feldman, Daniel C.
McGraw-Hill, 1983
Buku Teks
Miller, Heather S., author
Neal-Schuman Publishers, 1992
Buku Teks
Flynn, Nancy, author
American Management Association, 2006
eBooks
Callahan, Robert E.
Merrill , 1988
Buku Teks
savage, William W.
Scott Foresman & Co., 1968
Buku Teks