Eriksson, Sirkka-Liisa, and Heikki Orelma. 2011. “A Mean-Value Theorem for Some Eigenfunctions of the Laplace-Beltrami Operator on the Upper-Half Space”. Annales Fennici Mathematici 36 (1):101-10. https://doi.org/10.5186/aasfm.2011.3606.