R. Oktapratama, I. A. W. Chrismastianto, and D. Hidayat, “THE IMPLEMENTATION OF THE PROBLEM-BASED LEARNING METHOD TO ENHANCE GRADE 7 STUDENTS’ CRITICAL THINKING SKILLS IN LEARNING MATHEMATICS AT SMP HOLLAND VILLAGE MANADO”, JOHME, vol. 3, no. 1, pp. 108–117, Dec. 2019.