Citation

Jefferson Lab, Steve Gagnon. 2 Febuary 2008. <http://education.jlab.org/itselemental/ele002.html

Enyclopedia of the Earth, Sidney Dragon. 2 Febuary 2008. <http://www.eoearth.org/article/Helium

Holt and Rinehart and Winston. "introduction to Matter." Holt Science and Technology. 2002