T. P. Karpovets Taras Shevchenko Kyiv National Unaversity Ukraine
V. V. Konopelnyuk Taras Shevchenko Kyiv National Unaversity Ukraine
O. M. Savchuk Taras Shevchenko Kyiv National Unaversity Ukraine
L. I. Ostapchenko Taras Shevchenko Kyiv National Unaversity Ukraine