Voronin, K.V., and S.A. Solovyev. “Solution of the Helmholtz Problem Using the Preconditioned Low-Rank Approximation Technique”. Numerical Methods and Programming (Vychislitel’nye Metody i Programmirovanie) 16, no. 44 (May 24, 2015): 268–280. Accessed April 23, 2024. https://en.num-meth.ru/index.php/journal/article/view/832.