Ohaegbulam, Festus Ogboaja
University Press of America, 1980
Buku Teks
Amita Shastri, A. Jeyaratnam Wilson
Curzon Press, 2001
Buku Teks
Mayall, James
Cambridge University Press, 1990
Buku Teks
Costa, Horacio La de
Solidaridad Publishing House, 1965
Buku Teks
Deutsch, Karl Wolfgang, 1912-1992, author
MIT Press, 1972
Buku Teks