Yumniyati, K. .-., I. .-. Sujadi, and D. .-. Indriati. “COGNITIVE LEVEL PROFILE AT THE TENTH GRADE OF SENIOR HIGH SCHOOL STUDENTS IN MATHEMATICS PROBLEM SOLVING ON THREE VARIABLES OF LINEAR EQUATION SYSTEM”. International Online Journal of Education and Teaching, vol. 6, no. 3, July 2019, pp. 473-85, https://iojet.org/index.php/IOJET/article/view/535.