T. M. F. Caneppele, C. R. G. Torres, A. Chung, E. H. Goto, and S. C. Lekevicius, “Effect of photochemical activation of hydrogen peroxide bleaching gel with and without TiO2 and different wavelengths”, Braz. J. Oral Sci., vol. 9, no. 3, pp. 393–397, Nov. 2015.