Photoacoustic spectroscopy to evaluate the potentiality of bee-propolis as UV protector: In vivo test in humans E. Sehn, K.C. Silva, A.C. Bento, M.L. Baesso et S.L. Franco J. Phys. IV France, 125 (2005) 681-683 DOI: 10.1051/jp4:2005125156