Relaxation-diffusion processes in natural porous media: sedimentary rocks D. Pérez, A. Benavides and M. Martín-Landrove Eur. Phys. J. Appl. Phys., 42 3 (2008) 321-326 Published online: 06 May 2008 DOI: 10.1051/epjap:2008078