KOŠÍKOVÁ, Martina - PAVLUŠ, Miron. Approximation of the first derivate by differences and its application in management. In Journal of management and business : research and practice. - Prešov : Fakulta manažmentu Prešovskej univerzity, 2016. ISSN 1338-0494, 2016, vol. 8, no. 2, s. 5-22.