1.
Ivanov V. ON LOWER BOUNDS OF THE SECOND-ORDER DINI DIRECTIONAL DERIVATIVES. Ann. Sofia Univ. Fac. Math. and Inf. [Internet]. 2004 Dec. 12 [cited 2024 Nov. 21];96:163-71. Available from: https://stipendii.uni-sofia.bg/index.php/fmi/article/view/170