For content, images and editing services:
- http://www.eo.ucar.edu/rainbows/
- http://bestclipartblog.com/clipart-pics/rainbow-clip-art-3.gif
- http://www.hidrocrom.com/img/triangle_color.jpg
- http://www.myuniversalfacts.com/2006/04/how-rainbows-are-formed-what-causes.html http://www.physicsclassroom.com/Class/refrn/u14l4b.cfm
- http://img.dailymail.co.uk/i/pix/2007/08_01/rainbowG0608_684x700.jpg
- http://sweetclipart.com/multisite/sweetclipart/files/rainbow_full_circle.png
- http://www.ams.org/samplings/feature-column/fcarc-rainbows
- http://www.atoptics.co.uk/fz552.htm
- http://in-the-sky.org/baapdf/baa20041127_05.php
- http://www.webexhibits.org/causesofcolor/13A.html
- http://www.physics.org/article-questions.asp?id=58
- http://www.mrscienceshow.com/2010/07/science-of-double-rainbows-omg-what.html
- http://www.weather.com/news/science/skywatching-double-rainbow-20130513
- http://www.picmonkey.com/
- http://upload.wikimedia.org/wikipedia/commons/thumb/3/39/GodfreyKneller-IsaacNewton-1689.jpg/220px-GodfreyKneller-IsaacNewton-1689.jpg
- https://upload.wikimedia.org/wikipedia/commons/thumb/7/73/Frans_Hals_-_Portret_van_Ren%C3%A9_Descartes.jpg/245px-Frans_Hals_-_Portret_van_Ren%C3%A9_Descartes.jpg
- http://readanddigest.com/how-is-a-rainbow-formed/
