Tolan, Janet
Sage, 2003
Buku Teks SO
editor, Don C. Locke, Jane E. Myers, Edwin L. Herr
Sage, 2001
Buku Referensi
McLeod, John
Open University Press, 2005
Buku Teks
Brown, Jeannette A
Brooks.Cole, 1983
Buku Teks SO
Stone, Gerald L
Brooks/Cole, 1985
Buku Teks SO