Kornblum, William
Prentice-Hall, 1992
Buku Teks SO
Parrillo, Vincent N.
John Wiley & Sons, 1985
Buku Teks
Curran, Daniel J.
Allyn & Bacon, 1987
Buku Teks
Farley, John E.
Prentice-Hall, 1987
Buku Teks
Horton, Paul B.
Appleton-Century-Crofts, 1955
Buku Teks