Karaprtyan, G. A., and A. A. Darbinyan. “NOETHERICITY OF SEMI-ELLIPTICAL OPERATOR WITH CONSTANT COEFFICIENTS IN THE RANGE”. Proceedings of the YSU A: Physical and Mathematical Sciences 42, no. 3 (217) (October 6, 2023): 16–24. Accessed July 22, 2024. https://journals.ysu.am/index.php/proceedings-phys-math/article/view/vol42_no3_2008_p016-024.