1. https://nano.tu-dresden.de/pubs/slides/others_2009_04_30_IhsanBoustani.pdf
. Accessed on July 2015
2. Ras Tanura-Raffinerie, Saudi-Arabian,
http://www.posterlounge.de/rastanuraraffineriesaudiarabienpr156200.html
. Accessed on October 2014
3. The Discovery of Carbon,
http://en.wikipedia.org/wiki/Carbon
. Accessed on October 2014
4. http://pixgood.com/carbon-isotopes.html
. Accessed on October 2014
5. P. Enghag, Encyclopedia of the Elements (Wiley-VCH Verlag GmbH & Co, KGaA, Weinheim, 2004)