Ganievich, Rakhimov Davran. “ON CALCULATION OF MULTIPLE EIGENVALUES OF THE LINEAR OPERATOR-FUNCTION BY REDUCTION PSEUDO-PERTURBATION METHODS”. IIUM Engineering Journal 14, no. 2 (November 19, 2013). Accessed February 4, 2023. https://journals.iium.edu.my/ejournal/index.php/iiumej/article/view/438.