Lightbown, P., & Spada, N. M. (1999). How languages are learned. Oxford: Oxford University Press.
Roehr-Brackin, K & Tellier, A (2019). What’s the best way to teach children a second language? New research produces surprising results.
Retrieved from https://theconversation.com/
Skinner, B. F. (1957). Verbal behavior. New York: Appleton-Century-Crofts.