Amalya, C.P. et al. 2021. Implementation of the Problem Base Learning Model combined with E-STEM Based Student Worksheets on Learning Outcomes and Self Efficacy on Environmental Pollution Materials. Jurnal Penelitian Pendidikan IPA. 7, SpecialIssue (Nov. 2021), 37–38. DOI:https://doi.org/10.29303/jppipa.v7iSpecialIssue.962.