Kornblum, William
Harcourt Brace College Publishers, 1997
Buku Teks
Bryjak, George J
Allyn and Bacon, 1994
Buku Teks
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