Mejía, P., and M. Monterrsa. “Comparison of the Degree of Coronal Pigmentation in Extracted Premolars After the Application of Bi-Antibiotic and Tri-Antibiotic Pastes.”. Journal of Oral Research, Vol. 4, no. 2, Mar. 2015, pp. 116-23, doi:10.17126/joralres.2015.024.