Brown, Adrian, author
Facet Publishing, 2006
Buku Teks
Yerbury, Hilary, author
University of Technology, 1992
Buku Referensi
Indiana Purdue University Press, 2014
Buku Teks
Evans, G. Edward, 1937-, author
Neal-Schuman, 2013
Buku Teks
McLeod, John, author
McGraw-hill Open University press, 2012
Buku Teks