Rahmianti L. The Implementation of Problem Based Learning Using Integrated Student’s Worksheet (LKPD) Towards Student’s Critical Thinking of 2nd Grade at SMP N 12 Padang. universe [Internet]. 2020 Dec. 16 [cited 2026 Apr. 17];1(2):59-65. Available from: http://universe.ppj.unp.ac.id/index.php/universe/article/view/17