Luksetich, William A.
Little, Brown, 1982
Buku Teks
by Peter Knoepfel ... [and others]
Policy Press, 2007
Buku Teks
Bozeman, Barry
St. Martin's Press, 1979
Buku Teks
Gohagan, John Kenneth
McGraw-Hill, 1980
Buku Teks
Bromley, Daniel W., 1940-
Basil Blackwell, 1989
Buku Teks