Ralević, P. , Dobrodolac, M. , Švadlenka, L. , Šarac, D. and Đurić, D. 2020. Efficiency and productivity analysis of universal service obligation: a case of 29 designated operators in the European countries. Technological and Economic Development of Economy. 26, 4 (Jun. 2020), 785-807. DOI:https://doi.org/10.3846/tede.2020.12062.