McNair, Brian, author
A Member of the Hodder Headline Group, 1998
Buku Teks
London : Collier-Macmillan, 1967,
Buku Teks
Schrag, Clarence C., author
Harper & Row, 1963
Buku Teks
Ginsberg, Morris
Buku Teks
Zanden, James W. Vander, author
John Wiley & Sons, 1979
Buku Teks