Astrophysics Database Systemhttp://adsabs.harvard.edu/abstract_service.htmlhttp://livepage.apple.com/shapeimage_2_link_0
PGPLOThttp://star-www.rl.ac.uk/star/docs/sun15.htx/sun15.htmlhttp://www.astro.ucla.edu/~wright/CosmoCalc.htmlshapeimage_3_link_0
Astronomy Conferenceshttp://cadcwww.dao.nrc.ca/meetings/meetings.htmlhttp://www.astro.ucla.edu/~wright/CosmoCalc.htmlshapeimage_4_link_0
Astro-ph Archivehttp://xxx.lanl.gov/archive/astro-phhttp://xxx.lanl.gov/archive/astro-phshapeimage_5_link_0
NASA Extragalactic Databasehttp://nedwww.ipac.caltech.edu/http://nedwww.ipac.caltech.edu/shapeimage_6_link_0
Cosmology calculatorhttp://www.astro.ucla.edu/~wright/CosmoCalc.htmlhttp://www.astro.ucla.edu/~wright/CosmoCalc.htmlshapeimage_7_link_0

Useful links

Hubble Space Telescope

ESO

Institute for Astronomyhttp://www.roe.ac.uk/ifa/