Rosenberg, Jerry M.
McGraw-Hill, 1992
Buku Referensi
Jones, David J.
Second Back Row Press, 1981
Buku Teks
Jones, David J.
Australia, Second Back Row Press
Buku Referensi
Brown, Wendy E.
McGraw-Hill, 1993
Buku Referensi
Pugh, Eric
Oryx Press, 1981
Buku Referensi