[1]
M. N. Feller, “Necessary and sufficient conditions of harmonicity of functions of infinitely many variables (Jacobian case)”, Ukr. Mat. Zhurn., vol. 46, no. 6, pp. 785–788, Jun. 1994, Accessed: Feb. 17, 2026. [Online]. Available: https://umj.imath.kiev.ua/index.php/umj/article/view/5709