Brown, H. D. (2015). Teaching by Principles: An Interactive Approach to Language Pedagogy. Pearson Education ESL. Genesee, F. (2000). Early Bilingual Development: One Language or Two? Multilingual Matters. Lightbown, P. M., & Spada, N. (2013). How Languages are Learned. Oxford University Press. Wagner, H. (2010). Early Exposure to a Second Language: What, When, and in Which Context? Multilingual Matters. Cummins, J. (2008). BICS and CALP: Empirical and Theoretical Status of the Distinction. Academic Language and Learning Institute. McLaughlin, B. (1985). Second-Language Learning in Children: A Theoretical Model. Cambridge University Press. Pinter, A. (2008). Teaching Young Language Learners. Oxford University Press.