Muhammad Arshad, Atiqe Ur Rahman, and Muhammad Saeed, “An abstract approach to convex and concave sets under refined neutrosophic set environment”, Neutrosophic Sets Syst., vol. 53, pp. 274–296, Jan. 2023, Accessed: Dec. 30, 2024. [Online]. Available: https://fs.unm.edu/nss8/index.php/111/article/view/3227