BLIZNIKAS, V. The differential equations of some differential geometrical objects. Lithuanian Mathematical Journal, [S. l.], v. 6, n. 4, p. 497–501, 1966. DOI: 10.15388/LMJ.1966.19748. Disponível em: https://www.journals.vu.lt/LMJ/article/view/19748.. Acesso em: 4 may. 2024.