Ferriss, Hugh, author
Dover Publications, 2005
Buku Teks
Drake, St. Clair
Harper and Row, 1962
Buku Teks
Huxley, Aldous
New York, Harper & Brothers, 1956
Buku Teks
Wolfe, Gerard R., author
McGraw-Hill, 1994
Buku Referensi
edited by Robert Moore Fisher
Doubleday, 1955
Buku Teks