TY JOUR TI Tax burden optimization for small and medium-sized businesses: international experience and Russian practice KW small and medium-sized businesses KW optimization of the tax burden KW USN KW VAT KW insurance premiums KW patent taxation system KW European experience JO JOURNAL OF MONETARY ECONOMICS AND MANAGEMENT AU Basnukaev, M.S. AU Atueva, E.B. AU Omarov, Z.Z. PY 2026 IS 0 PB ITBO University