Putri, Amelia, and Amali Putra. 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), 77-83. https://doi.org/10.24036/universe.v2i1.59.