TY JOUR TI THE CONTENT OF THE CONCEPT OF TAX BURDEN KW tax burden KW general taxation system KW special tax regimes KW simplified taxation system (or STS) KW patent taxation system (or PSN) KW unified agricultural tax (or UTS) JO Russian Journal of Management AU Vandina, O.G. AU Snegireva, N.V. AU Shatalova, O.I. PY 2025 IS 13 PB Publishing Center RIOR