Sitthitikul, P. “Discussion Paper (Understanding L2 Acquisition in English Language Learners: The Interplay of Age-Related, Cognitive, and Sociocultural Factors and Their Implications for Instructional Practices)”. Journal of Studies in the English Language, vol. 4, June 2009, pp. 185-93, https://so04.tci-thaijo.org/index.php/jsel/article/view/22070.