Simangunsong, Agustina, and Penda Sudarto Hasugian. 2020. “Application of the Certainty Factor Method to Diagnose Escherichia Coli Bacteria in Refilled Drinking Water”. Jurnal Info Sains : Informatika Dan Sains 10 (1):7-12. https://doi.org/10.54209/infosains.v10i1.26.