1. Nature Mater. 8, 3–4 (2009).
2. http://www.universityofcalifornia.edu/news/article/19016
3. http://www.nytimes.com/2008/11/08/education/08college.html
4. http://www.boston.com/news/local/breaking_news/2008/11/harvard_freezes.html
5. http://www.worldenergyoutlook.org/