edited by Sohail H. Hashmi, Steven P. Lee
Cambridge University Press, 2004
Buku Teks
Townsend, Sue, author
Penguin , 2004
Buku Teks
Currance, Phillip L.
Elsevier , 2005
Buku Referensi
edited by Warren K. Agee, Phillip H. Ault, Edwin Emery
Harper and Row, 1982
Buku Teks
Fenner, M. Kathleen
D. Van Nostrand Comp., 1980
Buku Teks