Thumm, Garold W., author
Prentice-Hall, 1967
Buku Teks
Emerson
Little,Brown and Company, 1981
Buku Teks
Jennifer L. Lawless, author
Cambridge University Press, 2012
eBooks
Carr, Robert K., author
Rinehart, 1957
Buku Teks
Krislov, Samuel
The Free Press, 1968
Buku Teks