LigunA. A., and ShumeikoA. A. “Recovery of a Function from Information on Its Values at the Nodes of a Triangular Grid Based on Data Completion”. Ukrains’kyi Matematychnyi Zhurnal, Vol. 54, no. 3, Mar. 2002, pp. 332-41, https://umj.imath.kiev.ua/index.php/umj/article/view/4069.