1. J. Keating, et al., Proceedings of ISATA 29, June, 1996, Florence, Italy, paper no. 96EL011, pp. 47–55.
2. A. Brunia, et al., Proceedings of ISATA 27, September, 1994, Aachen, Germany, paper no. 94EL042, pp. 183–188.
3. G. Schaumberg, Proceedings of ISATA 27, September, 1994, Aachen, Germany, paper no. 94EL076, pp. 113–120.
4. J.P. Maceda, Proceedings of ISATA 29, June, 1996, Florence, Italy, paper no. 96EL074, pp. 507–514.
5. H.D. Olmstead, Electric and Hybrid Vehicle Technology Magazine (1995), no page reference.