Naimnule, M., K. Kartono, and M. Asikin. “Mathematics Problem Solving Ability in Terms of Adversity Quotient in Problem Based Learning Model With Peer Feedback”. Unnes Journal of Mathematics Education Research, Vol. 9, no. 2, Dec. 2020, pp. 222-8, https://journal.unnes.ac.id/sju/ujmer/article/view/33859.