1. Website of SFC Smart Fuel Cell AG, http://www.efoy.com.
2. Membranen für Polymerelektrolyt-Brennstoffzellen
3. Personal website of Walther G. Grot, working on the development of Nafion at DuPont, http://www.nafion.mysite.com/.
4. J. Garbak, U.S. DOE program manager, presentation at the DOE Hydrogen Program—2007 Annual Merit Review, 17.05.2007, Arlington, Virginia, USA, http://www.hydrogen.energy.gov/pdfs/review07/tv_0_garbak.pdf.
5. High temperature PEM fuel cells