Khosravi, Amir, and Farkhondeh Takhteh. “\(g\)-Bessel Sequences and Operators”. Communications in Mathematics and Applications 7, no. 2 (November 4, 2016): 139–149. Accessed May 2, 2024. https://www.rgnpublications.com/journals/index.php/cma/article/view/398.