1. U.S. Patent 2,177,068 by A. J. L. Hutchinson, The use of glycolamine-water blends. (October 24, 1939)
2. U.S. Patent 2,445,468 by C. L. Blohm, F. C. Riesenfeld and H. D. Frazier. The use of monohydric aliphatic alcohol-amine-water blends. (July 20, 1948)
3. U.S. Patent 2,550,446 by C. L. Blohm, F. C. Riesenfeld and H. D. Frazier. The use of amine-water-polyhydrie alcohol with a variety of secondary solvents. (April 24, 1951)
4. U.S. Patent 2,712,978 by C. L. Blohm and F. C. Riesenfeld. The use of an amino ether-water-polyhydric alcohol blend. (July 12, 1955)
5. South Africa Patent R61/2982 by C. H. Deal, Jr., E. L. Derr and M. N. Papadopoulos (Shell Int. Res. Maat. N.V.). The use of diethanol amine or di-isopropanol amine and water with either sulpholane or dimethyl formamide. (December 12, 1961)