1. R. Zazkis. (2010). A Tool Code-Switching Mathematical Language Using for. Learning, 20(3), 38-43.
2. O. Jegede. (2012). Roles of Code Switching in Multilingual Public Primary Schools in Ile-Ife, Nigeria. 1(3), 40-46.
3. L. Abad. (2010). An Analysis of Teachers’ and Students’ Perceptions of Codeswitching in Teaching Science and Mathematics in a Philippine Private High School. The Journal of Asia TEFL. 7(1), 239-264.
4. R. Leyaley. (2016). The English Language Proficiency of Freshmen Students in the Institute of Teacher Education, Kalinga Apayao State College. International Journal of Advanced Research in Management and Social Sciences. 5(2), 257-278.
5. L. Makewa, N. Role, E, & E. Tuguta. (2013). Students’ perceived level of English proficiency in secondary schools in Dodoma, Tanzania. International Journal of Instruction, 6(2), 35-52.