Sorauf
Little, Brown and Company, 1980
Buku Teks
Burns, James McGregor, author
Prentice-Hall, 1963
Buku Teks
CQ Press, 2003
Buku Teks
Bailey, Stephen K., author
Voice of America Forum Lectures, 1956
Buku Teks
by James E. Anderson; David Brady; Charles Bullock III; Joseph stewart, JR
Brooks/Cole; cengage learning, 1984
Buku Teks