Wiarda, Howard J., author
Hartcourt College Publishers, 2001
Buku Teks
by Christopher S. Allen [and others]
D.C. Health, 1987
Buku Teks
Roberts, Geoffrey
Manchester University Press, 1984
Buku Teks
Cini, Michelle, author
Oxford Univesity Press, 2010
Buku Teks
edited by Stephen White, Judy Batt and Paul G. Lewiss
Macmillan, 1993
Buku Teks