Dabutar, Nina Karina, et al. “Isolation and Identification of Coliform Bacteria in Simbara Water Source in Galiaman Hamlet, Kerajaan Sub-District, Pakpak Bharat Regency”. Jurnal Pembelajaran Biologi: Kajian Biologi Dan Pembelajarannya, vol. 11, no. 1, June 2024, https://jpb.ejournal.unsri.ac.id/index.php/jpb/article/view/45.