SAGALAYEV, V. A.; FIRSOV, G. A. Christian Steven (1781–1863) at the Lower Volga. Memoranda Societatis pro Fauna et Flora Fennica, [S. l.], v. 90, 2015. Disponível em: https://journal.fi/msff/article/view/48572. Acesso em: 7 touko. 2024.