Vidad, D. C., and M. A. T. Quimbo. “Students’ Problem-Solving Difficulties and Coping Strategies in Mathematics: A Model- Building Study”. International Journal of Learning, Teaching and Educational Research, vol. 20, no. 9, Sept. 2021, pp. 136-73, http://www.ijlter.myres.net/index.php/ijlter/article/view/28.