Ivanova-Karatopraklieva I. Infinitesimal bendings of rotational surfaces with changing signs curvature. Ann. Sofia Univ. Fac. Math. and Inf. [Internet]. 1995 Dec. 12 [cited 2024 Nov. 24];87:179-88. Available from: https://stipendii.uni-sofia.bg/index.php/fmi/article/view/412