“Safety and Efficacy of Photodynamic Therapy With ALA 10% Topical Gel Activated by Red Light Versus ALA 20% Topical Solution Activated by Blue Light for the Treatment of Actinic Keratosis on the Upper Extremities: A Blinded Randomized Study ”. SKIN The Journal of Cutaneous Medicine 8, no. 6 (November 18, 2024): s485. Accessed April 30, 2026. https://skin.dermsquared.com/skin/article/view/3060.