Araya Mungchamnankit, and Suwimon Nualpralaksana. “The change of crystal field of Gd3+ in natural zircon with heat treatment in oxidizing and reducing atmospheres monitored by ESR spectroscopy”. Journal of Current Science and Technology, vol. 9, no. 2, Feb. 2023, pp. 141-7, https://ph04.tci-thaijo.org/index.php/JCST/article/view/450.