Cullingworth, J.B., author
Allen & Unwin, 1973
Buku Teks
Curran, Daniel J., author
Allyn & Bacon, 1987
Buku Teks
Columbia University Press, 1968
Buku Teks
Gist, Noel P., author
Thomas Y. Crowell, 1956
Buku Teks
Gist, Noel P., author
Harper & Row , 1974
Buku Teks