K. Dhurai, and A. Karpagam. “New Membership Function and New Ranking Function on Heptagon Fuzzy Number”. International Journal of Mathematics And its Applications 5, no. 4 - F (December 30, 2017): 875–878. Accessed July 22, 2024. https://ijmaa.in/index.php/ijmaa/article/view/1351.