1. Albadejo, S., Coyle, Y., & de Larios, J. R. (2018). Songs, stories, and vocabulary acquisition in preschool learners of English as a foreign language. System, 76, 116–128.
2. Aline, D., & Hosada, Y. (2006). Team teaching participation patterns of homeroom teachers in English activities classes in Japanese public elementary schools. JALT Journal, 28, 5–22.
3. American Council on the Teaching of Foreign Languages (ACTFL) (2012). ACTFL performance descriptors for language learners. Retrieved June 23, 2019 from https://www.actfl.org/sites/default/files/pdfs/ACTFLPerformance-Descriptors.pdf
4. American Councils for International Education (2017). The national K-12 foreign language enrollment survey report. Retrieved June 26, 2019 from https://www.americancouncils.org/sites/default/files/FLE-report-June17.pdf
5. Armstrong, P. W., & Rogers, J. D. (1997). Basic skills revisited: The effects of foreign language instruction on reading, math, and language arts. Learning Languages, 2(3), 20–31.