1. www.city-solar-ag.de/eng/projects.htm
2. Editorial, Clean, green conferencing, Nature 432, 2004, 257.
3. www.mecanicaonline.com.br/2005/marco/pesada/airbus_a380.htm
4. Atmosfair - The atmosfair emissions calculator, www.atmosfair.de
5. www.pointcarbon.com, On June 28, 2005, the CO2 trading market price was 24.02 Euro/ton.