Bouhafsi, Y., M. Ech-chad, and M. Missouri. “A Remark on the Range Closures of an Elementary Operator”. Methods of Functional Analysis and Topology 27, no. 2 (June 25, 2021): 151–156. Accessed December 15, 2025. https://zen.imath.kiev.ua/index.php/mfat/article/view/791.