Star, WM, et al. “Topical 5-Aminolevulinic Acid Mediated Photodynamic Therapy of Superficial Basal Cell Carcinoma Using Two Light Fractions With a Two-Hour Interval: Long-Term Follow-up”. Acta Dermato-Venereologica, vol. 86, no. 5, Sept. 2006, pp. 412-7, doi:10.2340/00015555-0129.