Burns, James McGregor
Prentice-Hall, 1963
Buku Teks SO
Lieuwen, Edwin
Frederick A. Praeger, 1960
Buku Teks SO
CQ Press, 2003
Buku Teks
Bailey, Stephen K.
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