[ObviousScience]

Here are the first links that came up when Googling it:

http://www.lsst.org/lsst/science/scientist_dark_matter

http://scienceblogs.com/startswithabang/2011/04/20/how-gravi...

http://www.ifa.hawaii.edu/~ger/ASTRO-110_sp08/Lecture28_Dark...