Poincare’s scientific heritage and the modern mathemastics (in Bulgarian). Annual of Sofia University St. Kliment Ohridski. Faculty of Mathematics and Informatics, [S. l.], v. 97, p. 5–21, 2005. Disponível em: https://annual.uni-sofia.bg/index.php/fmi/article/view/141. Acesso em: 15 dec. 2025.