Filling a silo with a mixture of grains: Friction-induced segregation A. Károlyi, J. Kertész, S. Havlin, H. A. Makse and H. E. Stanley Europhys. Lett., 44 3 (1998) 386-392 Published online: 01 September 2002 DOI: 10.1209/epl/i1998-00483-y