Zorya, R. S., & Sitdikov, A. G. (2021). N.F. KALININ: STUDYING AND PRESERVING THE HISTORICAL AND ARCHAEOLOGICAL HERITAGE OF BOLGAR FORTIFIED SETTLEMENT. Arkheologiia Evraziiskikh Stepei (Archaeology of the Eurasian Steppes), (2), 346–360. https://doi.org/10.24852/2587-6112.2021.2.346.360