1. The Evaluation of Powders
2. R. P. Loveland. Symposium on Particle Size Measurement. Special Technical Publication No. 234, p. 57, A.S.T.M. Philadelphia Pa. (1958).
3. Small Particle Statistics;Herdan,1960
4. B.S. 3406 Part 1. Subdivision of gross sample. British Standards Institution (1963).