Modeling and design of learning content management systems: UML as a tool for learning system design. Annual of Sofia University St. Kliment Ohridski. Faculty of Mathematics and Informatics, [S. l.], v. 98, p. 231–242, 2008. Disponível em: https://annual.uni-sofia.bg/index.php/fmi/article/view/140. Acesso em: 11 jan. 2026.