Davidoff, Philip G.
Prentice-Hall, 1992
Buku Teks
Illman, Paul E., author
Tab Books, 1993
Buku Referensi
Ranz, John H.
W.H. Anderson Co., 1966
Buku Teks
edited by Coleen K. Withgott, Austin G. Anderson
Merriam-Webster, 1981
Buku Referensi
editor, Jerry Mintz
Macmillan, 1994
Buku Referensi