Olena O. Volvach. Formation and Management of a Business Portfolio of Electronic Payment Systems in the E-Commerce Market : Доктор філософії : spec.. 073 - Менеджмент : presented. 2024-04-19; popup.evolution: o; Taras Shevchenko National University of Kyiv. – Київ, 0824U001404.

Updated: 2026-11-09