Baron, Robert A.
Simon & Schuster, 1992
Buku Teks
Gray, Peter
Worth Publishers, 1999
Buku Teks
Ciccarelli, Saundra K.
Pearson - Prentice Hall, 2006
Buku Teks
Lefton, Lester A.
Allyn and bacon , 1997
Buku Teks
Munn, Norman L.
Houghton-Mifflin, 1961
Buku Teks