Jansén, C T, K Lammintausta, P Pasanen, K Neuvonen, E Varjonen, K Kalimo, and P Ayräs. 1991. “A Non-Invasive Chamber Sampling Technique for HPLC Analysis of Human Epidermal Urocanic Acid Isomers”. Acta Dermato-Venereologica 71 (2):143-45. https://doi.org/10.2340/0001555571143145.