On inner friction factor of fine powders and application for calculation of material movement in impact millsTamm, Jaan; Tümanok, Aleksei; Tadolder, JüriOST-95 Symposium on Machine Design : proceedings, Oulu, Finland, May 18-19, 19951995 / p. 112-121: ill https://www.ester.ee/record=b1033949*est