Chervenov, Nikolay, Vladimir Georgiev, and Andrey Vassilev. “In Memoriam Iordan Iordanov (1948-2021)”. Ann. Sofia Univ. Fac. Math. and Inf. 111 (December 4, 2024): 5–24. Accessed April 13, 2025. https://annual.uni-sofia.bg/index.php/fmi/article/view/995.