Gillespie, David C., author
Longman, 2003
Buku Teks
Colander, David C., author
Irwin, 1993
Buku Teks
Bryant, Steven J., author
Glencoe Press, 1969
Buku Teks
Bryant, Steven J., author
Glencoe Press, 1968
Buku Teks
Muzos, Steven J.
Harper Collins College, 1992
Buku Teks