1. H. Niederreither, Germ. Pat. 648, 941 (1932);
2. cf E. Citovich, Br. Pat. 303, 27 (1927);
3. W. Kangro, Germ. Pat. 914, 264 (1949).
4. Electrochemical Cells as Energy Converters Conf. Paper No. CP 56-266, AIEE Winter Gen. Meeting New York;Adams,1956
5. E. Justi, Germ. Pat. 1, 167, 406 (1956);