Achsin, M. A., K. Kartono, and H. Wibawanto. “Analysis of Problem Solving Capabilities in Problem Based Learning Contextual Approaches Based on Metacognitive Awareness”. Unnes Journal of Mathematics Education Research, Vol. 9, no. 2, Dec. 2020, pp. 147-55, https://journal.unnes.ac.id/sju/ujmer/article/view/32979.