In vitro determination of the sun protection factor of sunscreens through photoacoustic spectroscopy: A new approachS. L. Oliveira, A. M. Mansanares, E. C. da Silva and P. R. BarjaEur. Phys. J. Special Topics, 153 (2008) 475-478DOI: https://doi.org/10.1140/epjst/e2008-00488-2