Bramer, George R., author
Charles E. Merrill Publishing Company, 1981
Buku Teks
edited by J. Karl Nicholas and James R. Nicholl
Allyn and Bacon , 1994
Buku Teks
Tyner, Thomas E.
Buku Teks
Trzeciak, John, author
Phoenix, 1997
Buku Teks
Goldman, Stephen H., author
Houghton Miffiln, 1986
Buku Teks