Chasani, L., K. Kartono, and I. Kharisudin. “The Implementation of Immediate Feedback in Problem-Based Learning: The Problem-Solving Skill Analysis Seen from Self-Efficacy”. Unnes Journal of Mathematics Education Research, Vol. 11, no. 2, Dec. 2022, pp. 145-50, https://journal.unnes.ac.id/sju/ujmer/article/view/62027.