Umar Ahmad Kasule, author
Noordeen, 2008
Buku Teks
Patton, Kevin T.
Elsevier, 2010
Buku Referensi
Cummings, Michael R., author
Brooks/Cole, Cengage Learning, 2011
Buku Teks
Shier, David, author
McGraw-HIll. , 2001
Buku Teks
Luciano, Dorothy S., author
McGraw-Hill , 1978
Buku Teks