BondarenkoL. N., & ZhukP. F. (1997). Exact estima tes for the rate of convergence of the <em class="a-plus-plus">s</em&gt;-step method of steepest descent in eigenvalue problems. Ukrains’kyi Matematychnyi Zhurnal, 49(12), 1694–1699. Retrieved from https://umj.imath.kiev.ua/index.php/umj/article/view/5175