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
George, Stephen, author
Oxford University Press, 1985
Buku Teks