Kevin Martin, Natalina Purba, and Lisbet Novianti Sihombing. “Effect of Problem Based Learning on Student Learning Outcomes on Theme 2 Clean Air for Health Subtheme 1 the Body’s Way of Processing Clean Air Class V SD Negeri 4 Suhutnihuta Pardomuan”. Indonesian Journal of Advanced Research, vol. 2, no. 11, Nov. 2023, pp. 1465-76, doi:10.55927/ijar.v2i11.6616.