1) "A Mathematical Model of a Sealed Nickel-Cadmium Battery", Deyuan Fan and Ralph E. White, Journal of the Electrochemical Society, 1991, pages 17-25.

2) Understanding Renewable Energy Systems, Quashning, Volker, Earthscan Publications Ltd, 2005

3) .http://batteryuniversity.com/learn/article/how_to_measure_state_of_charge

Webliography:

1) www.batteryuniversity.com

2) http://en.wikipedia.org/wiki/Nickel_cadmium_battery

3) http://www.evdl.org/docs/nicad-principles.pdf