Littlefield, James E., author
Vakils, Feffer and Simons Private, 1971
Buku Teks
Wells, William D., author
Prentice-Hall, 2000
Buku Teks
Norris, James S., author
Prentice-Hall, 1980
Buku Teks
Weilbacher, William M
Macmillan, 1979
Buku Teks
Lane, W. Ronald, author
New York, 2000
Buku Teks