RYAZANOV, V. I.; SREBRO, U.; YAKUBOV, E. On the theory of the Beltrami equation. Ukrains’kyi Matematychnyi Zhurnal, [S. l.], v. 58, n. 11, p. 1571–1583, 2006. Disponível em: https://umj.imath.kiev.ua/index.php/umj/article/view/3555. Acesso em: 5 dec. 2025.