Davidson, Kenneth M.
West Publishing Company, 1974
Buku Teks
Van Horne, James C. (James Carter), 1935-, author
Prentice Hall International, 1995
Buku Teks
Jackson, John H., author
McGraw-Hill, 1983
Buku Teks
Schlesinger, Rudolf B.
The Foundation Press, 1950
Buku Teks
Kauper, Paul G., author
Little, Brown, 1971
Buku Teks