Esquierdo, Ida E., and Ronato S. Ballado. “Worktext in Precalculus: Evaluation and Acceptability”. Asian Journal of Education and Social Studies 16, no. 2 (March 27, 2021): 1-8. Accessed April 10, 2021. https://journalajess.com/index.php/AJESS/article/view/30395.