“Operator $\Box^{r}$ on a submanifold of Riemannian manifold and its applications”, Armen.J.Math., vol. 7, no. 1, pp. 6–31, May 2015, Accessed: Nov. 15, 2024. [Online]. Available: http://test.armjmath.sci.am/index.php/ajm/article/view/108