Sung Lim, Chang. “Synthesis of KLa(WO4)2:Ho3+ Yb3+ Phosphors via Microwave-Assisted Sol-Gel Route and Their Upconversion Photoluminescence Properties”. Asian Journal of Chemistry, vol. 27, no. 7, Mar. 2015, pp. 2603-7, doi:10.14233/ajchem.2015.18429.