Robbins, Stephen P., author
Prentice-Hall, 1998
Buku Teks
Ritchie, J.B.
West Publshing Company, 1980
Buku Teks
Gray, Jerry L., author
Charles E. Merrill, 1984
Buku Teks
Robbins, Stephen P., author
Prentice-Hall, 1988
Buku Teks
Carroll, Stephen J.
John Wiley and Sons, 1977
Buku Teks