XIA, LI, WANG XIGUI, and ZHANG YIN. 2010. “Preparation and Luminescence Properties of Europium(III) and Tungstate Co-Doped in Silicate Materials via The Sol-Gel Method”. Asian Journal of Chemistry 21 (5):3520-28. https://asianpubs.org/index.php/ajchem/article/view/17326.