Lefton, Lester A.
Allyn and bacon , 1997
Buku Teks
Wortman, Camille B., author
McGraw-Hill, 1992
Buku Teks
Myers, David G., author
Worth, 1986
Buku Teks
Santrock, John W., author
Worth Publishers, 1998
Buku Teks
Munn, Norman L., author
Houghton-Mifflin, 1961
Buku Teks