1. V. V. Sokolovskii, Plasticity Theory [in Russian], Vysshaya Shkola, Moscow (1969).
2. Z. Mroz and A. Dresher, Limit Plasticizing Approach to Some Cases of Flow Bulk Solids, Transactions of the ASME, Paper No. 68-MH-23.
3. Z. Mroz and C. Szymanski, “Gravity flow of granular materials in a converging channel,” Arch. Mech.,23 (1971).
4. L. V. Gyachev, Motion of Friable Materials in Tubes and Bunkers [in Russian], Mashinostroenie, Moscow (1968).
5. H. Haken, Synergetics. Instability Hierarchies in Self-Organizing Systems and Devices [Russian translation], Mir, Moscow (1985).