Harding, Alan, author
SAGE, 2014
Buku Teks
edited by Andrew Blowers, Chris Hammett and Philip Sarre
Hutchinson Educational in association with the Open University Press, 1974
Buku Teks
Gutkind, E. A.
The Free Press of Glencoe, 1963
Buku Teks
Orum, Anthony M., author
Blackwell, 2003
Buku Teks
Bergel, Egon Ernest, author
McGraw-Hill, 1955
Buku Teks