GRIGORENKO, N. V. Algebraic-geometric operators and Galois differential theory. Ukrains’kyi Matematychnyi Zhurnal, [S. l.], v. 61, n. 1, p. 14–27, 2009. Disponível em: https://umj.imath.kiev.ua/index.php/umj/article/view/2997. Acesso em: 27 apr. 2025.