1. Moos, Fuel Cells, Ed. Young, Vol. 2, p. 3, Reinhold Publishing Company, New York, 1963.
2. Heath and Worsham, ibid. p. 182.
3. Bockris and Conway, Record Chem. Progr. 25 (1964) 31.
4. Law and Perkin, Trans. Faraday Soc. 1 (1905) 31.
5. Gmelins Handbook, Vol. 1 (1848).