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