Mondy, R. Wayne, author
Boston Allyn and Bacon 1993,
Buku Teks
Greene, Mark R.
South-Western Publishing CO., 1983
Buku Teks
McGraw-Hill, 1994
Buku Teks
Rowe, R. Kerry
E & FN Spon, 1995
Buku Teks
Crawford, R. M.
Hutchinson University Library, 1963
Buku Teks