Dubois, Brenda, 1949-
Pearson, 2014
Buku Teks
Weinberger, Paul E., author
Macmillan, 1969
Buku Teks
Longres, John F.
F.E. Peacock Publisher, Inc, 1990
Buku Teks
David, Paul I
Brookings Institution, 1957
Buku Teks
Porterfield, John D.
Voice American Forum Lecture, [date of publication not identified]
Buku Teks