1. The internet, URL: http://www.afbis.com.nigeria/nigeria-energy.htm, 8 July 1998
2. Impacts of global electrification based upon photovoltaic technologies;Herwig;Renewable Energy,1997
3. Solar Energy Handbook;Kreider,1981
4. Official visit by author to the Office de l’Energie Solaire (ONERSOL), Niamey, Republic of Niger, 4–22 April 1984
5. Technical Information Officer (TIO), Basic Photovoltaic Principles and Methods, Report SERI/SP-290-1448, Solar Energy Research Institute, Golden, USA 1982