Keeton, William T.
W.W. Norton, 1967
Buku Teks
Freeman, Scott
Prentice-Hall, 2002
Buku Teks
Keeton, William T.
Penguin Books, 1976
Buku Teks
edited by John Brady
Cambridge University Press, 1982
Buku Teks
Winchester, A.M.
D. Van Nostrand , 1965
Buku Teks