Akar H. Karim, Nabeel E. Arif, and Ayad M. Ramadan. “The M-Polynomial and Nirmala Index of Certain Composite Graphs”. Tikrit Journal of Pure Science 27, no. 3 (November 29, 2022): 92–101. Accessed June 17, 2025. https://tjpsj.org/index.php/tjps/article/view/45.