SAFONOV, V. M.; TROHIMCHUK, Yu. Yu. On one criterion of constancy of a complex function. Ukrains’kyi Matematychnyi Zhurnal, [S. l.], v. 51, n. 8, p. 1096–1104, 1999. Disponível em: https://umj.imath.kiev.ua/index.php/umj/article/view/4700. Acesso em: 5 dec. 2025.