Dignan, Mark B., author
Lea & Febiger, 1981
Buku Teks
Johns, Edward B.
McGraw-Hill, 1966
Buku Teks
Greene, Walter H., author
Waveland Press, 1984
Buku Teks
edited by Derek Colquhoum, Karen Goltz and Margaret Sheehan
Harcourt Brace , 1997
Buku Teks
Russell, Robert D.
National Education Association, 1975
Buku Teks