Gaál, Magdolna, et al. “Photodynamic Therapy of Non-Melanoma Skin Cancer With Methyl Aminolaevulinate Is Associated With Less Pain Than With Aminolaevulinic Acid”. Acta Dermato-Venereologica, vol. 92, no. 2, Nov. 2011, pp. 173-5, doi:10.2340/00015555-1223.