Berman, B., N. Bhatia, D. Piacquadio, A. Houlihan, and D. Siegel. “Efficacy of ALA–PDT in the Treatment of Actinic Keratoses on the Upper Extremities: A Post Hoc Analysis of a Phase 3, Randomized, Vehicle-Controlled Trial”. SKIN The Journal of Cutaneous Medicine, vol. 4, no. 5, Sept. 2020, p. s66, doi:10.25251/skin.4.supp.65.