BEREZANSKY, Yu. M. On the theory of commutative Jacobi fields. Methods of Functional Analysis and Topology, [S. l.], v. 4, n. 1, p. 1–31, 1998. Disponível em: https://zen.imath.kiev.ua/index.php/mfat/article/view/52. Acesso em: 19 dec. 2025.