Chomsky, Noam. Selected Readings on Transformational Theory. Edited by J.P.B. Allen and Paul Van Buren. New York: Dover Publications, Inc., 1989. Print.
Krashen, Stephen D. Principles and Practice in Second Language Acquisition. Oxford: Pergamon, 1982. Print.
Krashen, Stephen D. Second Language Acquisition and Second Language Learning. Oxford: Pergamon Press, 1981. Print.
Nkrumah, Kwame. Neo-Colonialism, The Last Stage of Imperialism. London: Thomas Nelson & Sons, Ltd., 1965. Print