Filling a silo with a mixture of grains: Friction-induced segregationA. Károlyi, J. Kertész, S. Havlin, H. A. Makse and H. E. StanleyEurophys. Lett., 44 3 (1998) 386-392DOI: https://doi.org/10.1209/epl/i1998-00483-y