Mavis Biesanz
Prentice-Hall, 1969
Buku Teks
Hess, Beth B.
Macmillan Publishing Company, 1985
Buku Teks
Cohen, Bruce J., author
McGraw-Hill, 1988
Buku Teks
Schrag, Clarence C., author
Harper & Row, 1963
Buku Teks
Zanden, James W. Vander, author
John Wiley & Sons, 1979
Buku Teks