Parsons, B. S., and O. R. Gonzalez Gonzalez. “A Comparative Study of Mathematics Self-Efficacy and Anxiety Levels of Grades 10-12 Students at Thai Christian School Before and After Supplemental Practice Use of The Mathematics E-Learning Application Website Khan Academy”. Scholar: Human Sciences, vol. 10, no. 2, Dec. 2018, p. 207, http://www.assumptionjournal.au.edu/index.php/Scholar/article/view/2881.