McCormack, Gerard, author
Cambridge University Press, 2004
Buku Teks
Moreland, Canoll C., author
Oceana Publications, 1957
Buku Teks
LoPucki, Lynn M.
Little, Brown, 1995.
Buku Teks
Henson, Ray D.
St. Paul Minn, 1979
Buku Teks
Keenan, Denis, author
Pitman, 1992
Buku Teks