POLULYAKH, E. O. Trees as Level Sets for Pseudoharmonic Functions in the Plane. Ukrains’kyi Matematychnyi Zhurnal, [S. l.], v. 65, n. 7, p. 974–995, 2013. Disponível em: https://umj.imath.kiev.ua/index.php/umj/article/view/2483. Acesso em: 5 dec. 2025.