University of St. Andrews (UK)
University of St. Andrews: Hipparchus of Rhodes
This University of St. Andrews site contains biographical information as well as pictures and references for the Greek Mathematician Hipparchus. Click on "Full MacTutor biography" for the biography and on the picture for additional images.
Wikimedia
Wikipedia: Hipparchus (Astronomer)
Encyclopedia article about the Greek astronomer Hipparchus that contains information about his life and work. Also includes a lengthy list of references and links to additional information near the bottom of the page.