Mikailov Khidir Mustafa, Mammadov Ruslan Tavakkul, Rustamov Bayram Nizam and Rustamova Aysel Bayram (2023) “Spectral Variability of the Symbiotic Star CH Cyg”, Proceedings of the Pakistan Academy of Sciences: A. Physical and Computational Sciences, 60(1), pp. 9–13. doi: 10.53560/PPASA(60-1)671.