Min Kim, Young, et al. “Photocatalytic Degradation of Methylene Blue by Graphene Impregnated With CeO2 Nanoparticles under Ultrasonic Irradiation”. Asian Journal of Chemistry, vol. 25, no. 14, Aug. 2013, pp. 8178-80, doi:10.14233/ajchem.2013.15483.