Dumanyan, V. Zh. “ON THE ESTIMATION OF $\{|\triangledown u|^2dx$ FOR SOLUTIONS OF SECOND ORDER ELLIPTIC EQUATIONS”. Proceedings of the YSU A: Physical and Mathematical Sciences, vol. 42, no. 2 (216), Sept. 2023, pp. 145-7, doi:10.46991/PYSU:A/2008.42.2.145.