Liebert, Robert M., 1942-, author
Prentice-Hall, 1995
Buku Teks
RAy, William J.
Wadsworth, 1985
Buku Teks
Kalish, Harry I., author
McGraw-Hill, 1981
Buku Teks
edited by Sigmund Koch, David E. Leary
APA, 2006
Buku Teks
McMahon, Frank B., author
The Dorsey Press, 1986
Buku Teks