Iqbal, Mohammad, and Nurfitria Khoirunnisa. “Design And Construction Of An Expert System For Early Detection of Mental Illness in COVID-19 Patients And Handling Using Certainty Factor Method”. JURNAL TEKNOLOGI DAN OPEN SOURCE 4, no. 2 (December 20, 2021): 216 - 226. Accessed January 31, 2025. https://ejournal.uniks.ac.id/index.php/JTOS/article/view/1785.