Putri A, Putra A. DEVELOPMENT OF STUDENT WORKSHEET PROBLEM BASED LEARNING MODEL ORIENTED BY CRITICAL THIKING ACTIVITIES IN VIBRATION, WAVE, AND BEEF TOPIC IN CLASS VIII SMPN 3 PADANG. universe [Internet]. 2021 Jun. 17 [cited 2026 Apr. 17];2(1):77-83. Available from: http://universe.ppj.unp.ac.id/index.php/universe/article/view/59