TROYANSKI, S. Various memories of Rumen Maleev - the colleague and friend. Ann. Sofia Univ. Fac. Math. and Inf., [S. l.], v. 107, p. 9–13, 2020. DOI: 10.60063/gsu.fmi.107.9-13. Disponível em: https://stipendii.uni-sofia.bg/index.php/fmi/article/view/102. Acesso em: 30 apr. 2024.