1. Ahrens, C.D.: Meteorology Today—an Introduction to Weather, Climate, and the Environment, 8th edn. Thomson Brooks/Cole, Stamford (2007)
2. Beebe, R.R., et al.: The Impact of Selling the Federal Helium Reserve. National Academies Press, Washington (2000)
3. BICEP2:
http://www.cfa.harvard.edu/CMB/bicep2/science.html
4. CERN: The large hadron collider.
http://home.web.cern.ch/topics/large-hadron-collider
5. Hamak, J.E.: Helium, U.S. Geological survey, minerals yearbook 2012.
http://minerals.usgs.gov/minerals/pubs/commodity/helium/myb1-2012-heliu.pdf