Henning, Charles W.
McGraw-Hill Kogakusha, 1978
Buku Teks
Rodriguez, Rita M.
Prentice-Hall, 1976
Buku Teks
Madura, Jeff
South-Western College, 1998
Buku Teks
O`Connor, Dennis J.
Macmillan, 1990
Buku Teks
Madura, Jeff
Thomson South-Western, 2003
Buku Teks