Athira, S. K., K. Kamaraj, and P. P. R. Sam Johnson. “Algebraic Proofs of Characterizing Reverse Order Law for Closed Range Operators in Hilbert Spaces”. Eurasian Mathematical Journal, vol. 14, no. 3, Jan. 2023, pp. 08-25, https://emj.enu.kz/index.php/main/article/view/289.