Azalov, Pavel, and Fanny Zlatarova. “An Intelligent Object-Oriented Data Model”. Ann. Sofia Univ. Fac. Math. and Inf. 83, no. 1 (December 12, 1992): 113–121. Accessed November 22, 2024. https://annual.uni-sofia.bg/index.php/fmi/article/view/491.