Dark Matter and Dark Energy website:

http://jdem.gsfc.nasa.gov/general.html

http://nedwww.ipac.caltech.edu/level5/March04/Ellis/frames.html

http://www.damtp.cam.ac.uk/user/gr/public/bb_home.html

http://hyperphysics.phy-astr.gsu.edu/hbase/astro/bbcloc.html