Genchev T. On the investigations of Nikola Obreshkoff connected with the regularly monotonic functions (in Bulgarian, summary in English). Ann. Sofia Univ. Fac. Math. and Inf. [Internet]. 1997 Dec. 12 [cited 2024 Nov. 22];89:23-35. Available from: https://ftl5.uni-sofia.bg/index.php/fmi/article/view/352