ŠAPKAREV, I. ÜBER DIE INVARIANTEN RICCATISEHEN DIFFERENTIAGLEICHUNGEN. Matematichki Bilten, [S. l.], v. 16, n. 1, 1966. Disponível em: https://bilten.smm.org.mk/index.php/bilten/article/view/1292. Acesso em: 13 jun. 2026.