Kadets V. М.; Popov М. М. The Lyapunov theorem on convexity and its use for sign-embeddings . Ukrains’kyi Matematychnyi Zhurnal, [S. l.], v. 44, n. 9, p. 1192–1200, 1992. Disponível em: https://umj.imath.kiev.ua/index.php/umj/article/view/8169. Acesso em: 14 apr. 2025.