A. Pérez-Rodríguez, M. Flores-Acosta, R. Rodríguez-Mijangos, and R. Pérez-Salas, “Cu halide nanoparticle formation by diffusion of copper in alkali halide crystals”, Rev. Mex. Fís., vol. 52, no. 2, pp. 151–0, Jan. 2006.