Groze, S., and B. Janko. “Application of Iterative Methods for Solving Operator Equations and Improving Convergence Conditions”. Anal. Numér. Théor. Approx. 6, no. 1 (February 1, 1977): 15–21. Accessed May 19, 2024. https://ictp.acad.ro/jnaat/journal/article/view/1977-vol6-no1-art3.