PLAKHTA, L. P. Invariants of knots, surfaces in R 3, and foliations. Ukrains’kyi Matematychnyi Zhurnal, [S. l.], v. 59, n. 9, p. 1239–1252, 2007. Disponível em: https://umj.imath.kiev.ua/index.php/umj/article/view/3384. Acesso em: 5 dec. 2025.