1.
Stanilov G, Petrova I. A generalized Jacobi operator in the 4-dimensional Riemannian geometry. Ann. Sofia Univ. Fac. Math. and Inf. [Internet]. 1993 Dec. 12 [cited 2024 Dec. 5];85:55-64. Available from: https://ftl5.uni-sofia.bg/index.php/fmi/article/view/454