HOROZOV, E. Poincare’s scientific heritage and the modern mathemastics (in Bulgarian). Ann. Sofia Univ. Fac. Math. and Inf., [S. l.], v. 97, p. 5–21, 2005. Disponível em: https://stipendii.uni-sofia.bg/index.php/fmi/article/view/141. Acesso em: 4 dec. 2024.