Cooper, Barry, author
University of Missouri Press, 2004
Buku Teks
Dahl, Robert A., 1915-2014, author
Prentice Hall of India, 1976
Buku Teks
Dahl, Robert A., 1915-2014, author
Prentice-Hall, 1978
Buku Teks
Cowan, Douglas E., author
BlackWell Publishing, 2007
Buku Teks
edited by Peter Clarke and Stewart Sutherland
Routledge, 1991
Buku Teks