URL: https://www.researchgate.net/profile/Andrea-Del-Prete-4/publication/371223190/figure/fig1/AS:11431281164306858@1685675638964/The-green-surface-S-ph-that-solves-the-Dirichlet-problem-over-D-r-with-boundary-values-ph.png
URL2: https://www.researchgate.net/figure/The-green-surface-S-ph-that-solves-the-Dirichlet-problem-over-D-r-with-boundary-values-ph_fig1_371223190
