1. H. Kenneth, English Patent No. 977566 (1963).
2. F. Bashfort and J. Adams, Cambridge Univ. Press, London (1883).
3. Yu. A. Koshevnik and I. M. Kusakov, Zh. Fiz. Khim.,27, 1887 (1953).
4. S. Strausberg and E. Murbach, J. Engng. Chem. Proc. Developm.,2, No. 3, 228 (1963).