POLULYAKH, E. O. Trees as set levels for pseudoharmonic functions in the plane. II. Ukrains’kyi Matematychnyi Zhurnal, [S. l.], v. 68, n. 2, p. 254–270, 2016. Disponível em: https://umj.imath.kiev.ua/index.php/umj/article/view/1838. Acesso em: 5 dec. 2025.