Appendix: Letters of F.A.Stepun for S.L.Frank and T.S.Frank. History of Philosophy Yearbook / Istoriko-filosofskii ezhegodnik, [S. l.], v. 22, p. 424–458, 2024. Disponível em: https://ife.iphras.ru/article/view/7396.. Acesso em: 8 sep. 2024.