edited by Karl W. Deutsch and William J. Foltz
Atherton Press, 1966
Buku Teks
Conn, Steven
University of Pennsylvania Press, 2003
Buku Teks
Hardgrave, Robert L.
Harcourt College, 2000
Buku Teks
Hardgrave, Robert L.
Harcourt, Brace, 1970
Buku Teks
edited by Richard Allen
Routledge, 2000
Buku Teks