Chasani, Luluk, Kartono Kartono, and Iqbal Kharisudin. 2022. “The Implementation of Immediate Feedback in Problem-Based Learning: The Problem-Solving Skill Analysis Seen from Self-Efficacy”. Unnes Journal of Mathematics Education Research 11 (2), 145-50. http://journal.unnes.ac.id/sju/ujmer/article/view/62027.