George, Jim, author
Lynne Reinner, 1994
Buku Teks
Reynolds, P.A., author
Longman, 1994
Buku Teks
Couloumbis, Theodore A., author
Prentice-Hall, 1990
Buku Teks
Pearson, Frederic S., author
McGraw-Hill, 1992
Buku Teks
edited by John Baylis and Steve Smith
Oxford University Press, 2006
Buku Teks