1. C. E. Mensing, Patent USA No. 2405158 (1946).
2. A. E. Holley and O. E. Mott, English patent No. 321200, May (1929).
3. B. N. Laskorin et al., in collection: Extraction [in Russian], Moscow, Atomizdat (1962), No. 2.
4. B. N. Laskorin, et al., AE,12, No. 6 (1962).
5. R. E. Treybal, Chem. Eng. Progr., No. T-5 (1964).