Mahmoud Hassan Osman Fadl, Mubarak Dirar Abd-Alla, Fatma Osman Mahmoud Mohamed, Faiz M. B. Elshafia, and HassabAlla M.A.Mahmoud, “The effect of changing the nano size on the absorption coefficient and the energy gap of crushed Na Cl samples”, Euro.J.Ph.Ch.Ma., vol. 7, pp. 1–13, Jun. 2022.