GUBAIDULLIN , A. M. Studies of bolgar Fortified Settlements Defensive Structures by A.P. Smirnov . Arkheologiia Evraziiskikh Stepei (Archaeology of the Eurasian Steppes), [S. l.], n. 6, p. 221–230, 2023. DOI: 10.24852/2587-6112.2023.6.221.230. Disponível em: https://evrazstep.ru/index.php/aes/article/view/1151. Acesso em: 20 may. 2024.