IVANOVA-KARATOPRAKLIEVA, I. Infinitesimal bendings of some classes of rotational surfaces with mixed curvature. Ann. Sofia Univ. Fac. Math. and Inf., [S. l.], v. 85, p. 89–106, 1993. Disponível em: https://stipendii.uni-sofia.bg/index.php/fmi/article/view/458. Acesso em: 5 dec. 2024.