Mann, Richard
Gateway Books, 2000
Buku Teks
Ver Steeg, Clarence L.
Harper and Row, 1981
Buku Teks
Angle, Paul M
Fawcett Publications,Inc, 1960
Buku Teks
edited by Karl W. Deutsch and William J. Foltz
Atherton Press, 1966
Buku Teks
Mette Hjort, Scott MacKenzie, editor
Routledge, 2000
Buku Teks