L. Jokar, M. Bayani, H. Hamidi, M. Keivan, and S. Azari-Marhabi, “A Comparison of 940 nm Diode Laser and Cryosurgery With Liquid Nitrogen in the Treatment of Gingival Physiologic Hyperpigmentation Using Split Mouth Technique: 12 Months Follow Up”, J laser Med Sci, vol. 10, no. 2, pp. 131–138, Mar. 2019.