Крячок, О. С., and Євтушенко B. O. “About Development a Formal Model of Ontology for Semantic Search Systems”. Problems of Informatization and Management 1, no. 33 (October 27, 2011): 86–89. Accessed February 15, 2026. https://jrnl.nau.edu.ua/index.php/PIU/article/view/9178.