Ahn, H. and Brennen, C.E., et el. (1987) Experiments on Chute Flows of Granular Materials; ISBN 0444705236; Micromechanics of granular materials : proceedings of the U.S./Japan Seminar on the Micromechanics of Granular Materials, Sendai-Zao, Japan, October 26-30, 1987; 339-348