HINEVA, S. A NOTE ON THE SECTIONAL CURVATURE. Ann. Sofia Univ. Fac. Math. and Inf., [S. l.], v. 100, p. 11–20, 2011. Disponível em: https://stipendii.uni-sofia.bg/index.php/fmi/article/view/242. Acesso em: 23 dec. 2024.