Meng1, Ze-Da, et al. “Rare Earth Oxide-Doped Fullerene and Titania Composites and Photocatalytic Properties of Methylene Blue Under Visible Light”. Asian Journal of Chemistry, vol. 23, no. 5, Jan. 2011, pp. 2327-31, https://asianpubs.org/index.php/ajchem/article/view/10363.