MATVEEV, Vasilii N. The Omphalos in the Floor Decor of the Churches of the Premongol Rus Period. Actual Problems of Theory and History of Art, [S. l.], v. 6, p. 206–217, 2016. DOI: 10.18688/aa166-3-22. Disponível em: https://publ.actual-art.org/aptha/article/view/10535. Acesso em: 5 dec. 2025.