Binary granular gas mixtures: Theory, layering effects and some open questions D. Serero, S.H. Noskowicz, M.-L. Tan and I. Goldhirsch Eur. Phys. J. Special Topics, 179 (2009) 221-247 Published online: 31 May 2010 DOI: 10.1140/epjst/e2010-01205-4