Browder, Olin L.
West Publishing Co, 1984
Buku Teks
Casner, A. James, author
Little, Brown and Company, 1969
Buku Teks
Keeton, Robert E., author
West Pub. Co., 1960
Buku Teks
Vagts, Detlev F., author
The Foundation Press, INC, 1973
Buku Teks
Babb, Hugh W., author
Foundation Press , 1959
Buku Teks