1. http://www.asiapacificpartnership.org/pdf/REDGTF/6th_meeting/S16_NGK_Insulators.pdf
2. http://www.energy.ca.gov/research/notices/2005-02-24_workshop/11%20Mears-NAS%20Battery%20Feb05.pdf
3. http://prod.sandia.gov/techlib/access-control.cgi/2006/066740.pdf