Burke, Barlow, Jr.
St. Paul, Minn, 1994
Buku Teks
Soderquist, Larry D.
Va. : Michie, c, 1991
Buku Teks
Kauper, Paul G., author
Little, Brown, 1971
Buku Teks
Barrett, Edward L., author
Foundation Press, 1977
Buku Teks
Kauper, Paul G., author
Little, Brown, 1966
Buku Teks