Yopp, Ruth Helen, author
Allyn and Bacon, 1992
Buku Teks
editors, Peter Bruza, Marc Weeber
Springer, 2008
Buku Teks
Hadfield, Jill
International Thomson Publishing Company, 1995
Buku Teks
Wallace, Catherine, author
1992
Buku Teks
Wallace, Catherine, author
Oxford University Press, 1993
Buku Teks