Bişgin, Mustafa Cemil, and Abdulcabbar Sönmez. “Compactness of Quadruple Band Matrix Operator and Geometric Properties”. Annales Universitatis Paedagogicae Cracoviensis Studia Mathematica 21 (August 29, 2022): 17–32. Accessed April 28, 2024. https://studmath.uken.krakow.pl/article/view/9488.