"Review of Verbal behavior" by Skinner.
Verbal Behavior. New York: Apleton-Century-Crofts (Skinner 1957).
Bilingualism and Special Education: Issues in Assessment and Pedagogy.
How languages are learned. Oxford (Lightbrown & Spada 2013).
Second Language Acquisition and Second Language Learning. University of Southern California (Krashen 1981).