Schrag, Clarence C.
Harper & Row, 1963
Buku Teks
Zanden, James W. Vander
John Wiley & Sons, 1979
Buku Teks
Ogburn, William F.
Houghton Mifflin, 1946
Buku Teks
Brikerhaff, David B
West Publishing, 1988
Buku Teks
Doob, Christopher Bates
Holt, Rinehart and Winston, 1984
Buku Teks