Maurer, Herrymon, author
Macmillan, 1956
Buku Teks
Carroll, Archie B., author
Thomson , 2003
Buku Teks
edited by G. William Dauphinais and Colin Price
Simon & Schuster , 1998
Buku Teks
Harvard Business School Press, 2003
Buku Teks
McGraw-Hill, 1960
Buku Teks