Buchman, Joseph, author
Englewood Cliffs, NJ, Prentice-Hall
Buku Teks
Brown, Robert Goodell, author
New York, N.Y., Holt, Rinehart and Winston
Buku Teks
Usher, M.B.
Chapman and Hall , 1973
Buku Teks
Bruckner, Andrew M
Ptrentice-Hall International, INC, 1997
Buku Teks
Thompson, Chantal P.
D.C. heath and Company, 1996
Buku Teks