“Up Conversion Enhancement in Lanthanide Ions Doped Heavy Metal Oxides: Advances in Synthesis and Applications of Lanthanide-Doped Upconverting Nanoparticles”. Journal of Advances and Scholarly Researches in Allied Education, vol. 16, no. 9, June 2019, pp. 1719-25, https://ignited.in/index.php/jasrae/article/view/12461.