The experimental support for general relativity up to the early 1990s is summarized in:
Theory and Experiment in Gravitational Physics, Revised Edition,
C. M. Will
(Cambridge University Press, Cambridge, 1993).
A more up-to-date treatment of the subject can be found in:
``The Confrontation between General Relativity and Experiment,''
C. M. Will,
Living
Reviews in Relativity 4, 4 (2001).
Available online at
http://www.livingreviews.org/lrr-2001-4