Al-Delfi, Jawad. “A Quasi-Hilbert Space and Its Properties”. Al-Qadisiyah Journal of Pure Science 26, no. 4 (July 22, 2021): 169–174. Accessed January 18, 2026. https://www.journalsc.qu.edu.iq.51-77-64-103.cpanel.site/index.php/JOPS/article/view/1388.