H. . Hekmatnia, M. N. . Mousavi, K. Jafarpour Ghalehteimouri, A. Shamsoddini, A. B. . Kashkouli, and A. . Jamshidi, “Population Aging Tendencies in Islamic Countries Between 1950-2020: A Geographical Assessment”, JPSS, vol. 30, pp. 36–53, Sep. 2021.