Hembars’ka, S. B. “On Boundary Values of Three-Harmonic Poisson Integral on the boundary of a Unit Disk”. Ukrains’kyi Matematychnyi Zhurnal 70, no. 7 (July 25, 2018): 876-884. Accessed April 18, 2024. https://umj.imath.kiev.ua/index.php/umj/article/view/1602.