Zawawi, Rabiatul Adawiyah, et al. “Effect of Cr-Doped on Crystalline Phase, Surface Morphology and Electrical Properties of Charge-Ordered Nd0.75Na0.25MnO3 Ceramics”. Journal of Science and Technology, vol. 9, no. 3, Dec. 2017, https://publisher.uthm.edu.my/ojs/index.php/JST/article/view/2042.