Study of the scientific work by quantitative methods: some results on Academician Nikola Obreshkoff’s works. Annual of Sofia University St. Kliment Ohridski. Faculty of Mathematics and Informatics, [S. l.], v. 89, p. 117–127, 1997. Disponível em: https://annual.uni-sofia.bg/index.php/fmi/article/view/361. Acesso em: 11 jan. 2026.