In Memoriam: Rumen Maleev (1943-2019). Ann. Sofia Univ. Fac. Math. and Inf., [S. l.], v. 107, p. 5–8, 2020. DOI: 10.60063/gsu.fmi.107.5-8. Disponível em: https://stipendii.uni-sofia.bg/index.php/fmi/article/view/101. Acesso em: 7 may. 2024.