Nawar , A. S., and H. M. Atallah. “On \(\delta\beta\)-Open Sets in Tri Topological Spaces”. Journal of Advanced Studies in Topology 12, no. 1-2 (July 27, 2022): 8–17. Accessed November 30, 2023. https://m-sciences.com/index.php/jast/article/view/284.