56. Impeller pumps. Centrifugal and axial-flow pumps. Terminology and Symbols. Editor-in-chief assistant professor, Dr. of engineering science N.A. Nekrasova
Electronic Issue, M. -ETS Publishing House, 2001 Paper Issue: Edition N56. Moscow, Publishing House of Academy of Sciences of USSR , 1961, pp.32, terms 138 (Appendix - Letter Symbols), (in Russian).