k.Arjunan, b.Deeba, s. Naganathan,. “A Research on Bipolar Valued Vague Normal Subrings of A Ring”. Mathematical Statistician and Engineering Applications 72, no. 1 (July 5, 2023): 1926–1933. Accessed May 19, 2024. https://www.philstat.org/index.php/MSEA/article/view/2611.