1. C. F. Ng and P. K. Ng, Int. J. Lang. Lit. Linguist. 1, 98–105 (2015).
2. Z. Hamilton, Blended Learning: Internal Factors Affecting Implementation (Otterbein University, Ohio, 2019).
3. T. Olufemioladebinu, A. A. Adediran and W. O. Oyediran, J. Educ. Hum. Develop. 7, 109–115 (2018).
4. J. S. Suan, "Factors Affecting Underachievement in Mathematician" Proceeding of the 5th International Conference on Management and Muamalah (Kolej Universiti Islam Antarabangsa Selangor, Selangor, 2018), pp. 100–106.
5. J. Murray, Int. J. Bus. Soc. Sci. 4, 150–164 (2013).