K. B. Bashir, M. -ul-Islam, M. Ajmal, M. Waqas Nafees, A. Iftikhar, I. Gul, S. N. Naseem, and K. Mehmood, Effect of Cr3+ substitution on magnetic and electrical properties of (Ni0.3Cu0.7) Fe2O4 spinel ferrites, Rev. Mex. Fís. 66, (2020).