Kohls, Richard L.
New York, N.Y. Macmillan c.1972,
Buku Teks
Blau, Peter M., author
Routledge & Kegan Paul, 1966
Buku Teks
Lynch, Richard M.
McGraw-Hill, 1983
Buku Teks
Blau, Peter M., author
Routledge & Kegan Paul, 1963
Buku Teks
Guiltinan, Joseph P.
McGraw-Hill , 1991
Buku Teks