Putri, A. and Putra, A. (2021) “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, 2(1), pp. 77-83. doi: 10.24036/universe.v2i1.59.