“Up Conversion Enhancement in Lanthanide Ions Doped Heavy Metal Oxides: Advances in Synthesis and Applications of Lanthanide-Doped Upconverting Nanoparticles”. 2019. Journal of Advances and Scholarly Researches in Allied Education 16 (9): 1719-25. https://ignited.in/index.php/jasrae/article/view/12461.