1) K. Kordesch, V. Hacker, J. Gsellmann, M. Cifrain, G. Faleschini, P. Enzinger, R. Fankhauser, M. Ortner, M. Muhr and R. R. Aronson: J. Power Sources 86 (2000) 162–165.
2) R. Metkemeijer and P. Achard: Int. J. Hydrogen Energy 19 (1994) 535–542.
3) R. Metkemeijer and P. Achard: J. Power Sources 49 (1994) 271–282.
4) K. Kordesch, J. Gsellmann, M. Cifrain, S. Voss, V. Hacker, R. R. Aronson, C. Fabjan, T. Hejze and J. Daniel-Ivad: J. Power Sources 80 (1999) 190–197.
5) K. Machida, M. Itoh, K. Hirose and G. Adachi: Chem. Lett. 1117–1118 (1998).