Astrophysics Data System
The Astrophysics Data System (ADS) consists of four searchable databases of abstracts of articles in astronomy and astrophysics, instrumentation, and physics and geophysics. Some full-text articles, as well as astronomy preprints, are available, including digitized historical astronomy and astrophysics literature.
- Available to everyone.
- Harvard-Smithsonian Center for Astrophysics