Artikel Jurnal
Charles W. Kegley and Eugene R. Wittkopf, editor
McGraw-Hill, [2001, 2001]
Buku Teks
Weihrich, Heinz
McGraw-Hill, 1993
Buku Teks
Dahringer, Lee D.
Addison-Wesley, 1991
Buku Teks
edited by Charles W. Kegley and Eugene R. Wittkopf
McGraw-Hill, 1992
Buku Teks