Blackmore, D., Prykarpatsky, A. K., Prykarpatsky, Y. A., & Samoilenko, A. M. (2019). Theory of multidimensional Delsarte – Lions transmutation operators. II. Ukrains’kyi Matematychnyi Zhurnal, 71(6), 808-839. Retrieved from https://umj.imath.kiev.ua/index.php/umj/article/view/1478