Houghton Mifflin, 1985
Buku Teks
edited by John Louis Beatty, Oliver A. Johnson
Prentice-Hall, 1966
Buku Teks
Major, J. Russel, author
J.B. Lippincott, 1966
Buku Teks
Naidis, Mark, author
Dryden Press, 1972
Buku Teks
editor in chief, Mortimer J. Adler
Encyclopedia Britanica, 1990
Buku Referensi