Elzayat, Ghada Ahmed, et al. “Clinical Performance of Direct Anterior Composite Restorations Using Esthetic Dual-Shade Versus Polychromatic Natural Layering Technique: A Split Mouth Randomized Controlled Clinical Trial”. Brazilian Dental Science, vol. 23, no. 4, Sept. 2020, p. 12p, doi:10.14295/bds.2020.v23i4.2064.