ADS Digital Library:
Scanned, online books relating to astronomy for browsing and printing on demand
ARIBIB
ARI Bibliographic Database for Astronomical References
ASP"s A Selected List of Web Sites for Instructors of Introductory Astronomy Courses
Level5
Knowledge Base on Extragalactic Astronomy and Cosmology
LIGO Document Search
LIGO Publications Search
LIGO Theses
NED
NASA/IPAC Extragalactic Database
NRAO RAPs
STScI STEPsheet Search
U of T Astronomy and Astrophysics Book and Software Reviews