Wilkinson, Joseph W.
John Wiley & Sons, 1991
Buku Teks
Gelinas, Ulric J.
South-Western , 2005
Buku Teks
Carrithers, Wallace M.
Charles E. Merrill, 1967
Buku Teks
Page, John R., 1949-
Prentice-Hall, 1987
Buku Teks
Hall, James A.
South-Western College , 2001
Buku Teks