Cullen, Pauline, author
Cambridge University Press, 2008
Multimedia
Cullen, Pauline, author
Cambridge university press, 2010
Buku Teks
Sharpe, Pamela J., author
Barron's, 2001
Buku Teks
Swan, Michael, author
Cambridge University Press, 1992
Buku Teks
Pyle, Michael A., author
Lincoln : Nebraska, 1991,
Buku Teks