Champion, Dean J., author
McGraw-Hill, 1975
Buku Teks
Dubin, Robert, author
Prentice-Hall, 1959
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