1. E. W. Justi and E. A. Winsel, ?Kalte Verbrennung-Fuel Cells?, Franz Steiner Verlag, Wiesbaden (1962) p. 248.
2. J. S. Bone, S. Gilman, L. W. Niedrach and M. D. Read, in:Proceedings of the Annual Power Source Conf. 14 (1961) 47.
3. E. Findl and M. Klein; in:Proceedings of the 20th Annual Power Source Conf., PSC Publications Committee, Red Bank (1966) p. 49.
4. K. Kordesch, K.-H. Steininger and K. Tomantschger, in:Proceedings of the 23rd Intersociety Energy Conversion Eng. Conf. 2 (1988) p. 283.
5. A. Leonida, in:Proceedings of the European Space Power Conf. (1989) Madrid 1989, p. 227.