Couloumbis, Theodore A., author
Prentice-Hall, 1990
Buku Teks
Mingst, Karen A., author
W.W. Norton, 2004
Buku Teks
Papp, Daniel S., author
Macmillan, 1984
Buku Teks
Papp, Daniel S., author
Allyn and Bacon, 1997
Buku Teks
Papp, Daniel S., author
Macmillan, 1988
Buku Teks