Treffel, P, F Panisset, P Humbert, O Remoussenard, Y Bechtel, and P Agache. 1993. “Effect of Pressure on in Vitro Percutaneous Absorption of Caffeine”. Acta Dermato-Venereologica 73 (3):200-202. https://doi.org/10.2340/000155555573200202.