Mazzarello, V., G. Piga, M. Ferrari, E. Curreli, S. Dettori, F. Longoni, P. Delaconi, M. Sotgiu, and P. Bandiera. “Hydration, PH, Pigmentation, Sebum and Skin Texture: An in Vivo Non Invasive Study in Centenaries”. Italian Journal of Anatomy and Embryology, vol. 117, no. 2, Feb. 2013, p. 122, https://oajournals.fupress.net/index.php/ijae/article/view/4308.