Engel, Thomas, author
Prentice-Hall, 2010
Buku Teks
Balzhiser, Richard E., author
Prentice Hall of India, 1977
Buku Teks
Haberman, William L., 1922-, author
Boston: Allyn and Bacon, 1980
Buku Teks
Sushkov, V.V.
"Moscow: Peace Publishers/Foreign & Languages, [19?-]"
Buku Teks
Myers, Glen E., author
Prentice-Hall, 1989
Buku Teks