A. Pena, R. Garcia-Rojo, F. Alonso-Marroquin, and H. Herrmann. POWDERS AND GRAINS 2009, volume 1145 of AIP Conference Proceedings, page 185+. 2 HUNTINGTON QUADRANGLE, STE 1NO1, MELVILLE, NY 11747-4501 USA, Assoc Study Micromech Granular Media; Univ Twente; Colorado Sch Mines, AMER INST PHYSICS, (2009)6th International Conference on the Micromechanics of Granular Media,
Golden, CO, JUL 13-17, 2009.