Jilani, S. A. ., Khursheed, . K. . and Mukhtar, K. . (2021) “Comparative Study of F2–Layer Critical Frequency: Solar Cycle 22 : F2–Layer Critical Frequency ”, Proceedings of the Pakistan Academy of Sciences: A. Physical and Computational Sciences, 55(1), pp. 35–46. Available at: http://ppaspk.org/index.php/PPAS-A/article/view/199 (Accessed: 4 December 2025).