Dean, John J.
Boolarong Publications, 1987
Buku Teks
Anderson, Chris, author
Headline Publishing Group, 2016
Buku Teks
Sprague, Jo, author
Wadsworth/Cengage Learning, 2013
Buku Teks
Booher, Diana
Prentice-Hall, 1991
Buku Teks
Sprague, Jo, author
Wadsworth and Cengage Learning, 2013
Buku Referensi