F. H., Mohammed. “A Spectroscopic Study of the Effect of Er+3 Ions Concentration on the Optical and Structural Properties of NanoTiO2”. University of Thi-Qar Journal 18, no. 1 (July 26, 2023). Accessed November 22, 2025. https://www.jutq.utq.edu.iq/index.php/main/article/view/331.