Safitri V, lestari T. THE EFFECT PROBLEM BASED LEARNING ASSISTED BY QUESTION CARDS ON CRITICAL THINGKING SKILLS ON ADDITIVE AND ADDICTIVE SUBSTANCES FOR VIII GRADE STUDENTS OF SMPN 38 PADANG. universe [Internet]. 2024 Jun. 30 [cited 2026 Apr. 17];5(1):51-7. Available from: http://universe.ppj.unp.ac.id/index.php/universe/article/view/585