Lester, James D.
Scott, Foresman and Company, 1971
Buku Teks
Laster, James D
Scott, Foresman and Company, 1984
Buku Teks
Rosnow, Ralph L., author
Wadsworth, 1992
Buku Teks
Churchill Livingstone, 2003
Buku Teks
Netzley, Michael, author
Prentice-Hall, 2001
Buku Teks