FELLER, M. N. Necessary and sufficient conditions of harmonicity of functions of infinitely many variables (Jacobian case). Ukrains’kyi Matematychnyi Zhurnal, [S. l.], v. 46, n. 6, p. 785–788, 1994. Disponível em: https://umj.imath.kiev.ua/index.php/umj/article/view/5709. Acesso em: 6 dec. 2025.