rajagopal, raji, and S Baskaran. “Ontology Based E-Learning Systems in the Semantic Web”. International Journal of Computer (IJC) 6, no. 1 (October 17, 2012): 1–8. Accessed April 19, 2024. https://www.ijcjournal.org/index.php/InternationalJournalOfComputer/article/view/77.