This database is freely available to the general public via the Internet.

From ADS: 

The SAO/NASA Astrophysics Data System (ADS) is a digital library portal for researchers in astronomy and physics, operated by the Smithsonian Astrophysical Observatory (SAO) under a NASA grant.

ADS maintains three bibliographic collections containing more than 15 million records covering publications in astronomy and astrophysics, physics, and general science, including all arXiv e-prints. Abstracts and full-text of major astronomy and physics publications are indexed and searchable through the new ADS modern search form as well as a classic search form. A browsable paper form is also available.  ADS HELP Pages. 

In addition to maintaining its bibliographic corpus, ADS tracks citations and usage of its records to provide advanced discovery and evaluation capabilities. Integrated in its collections, ADS provides access and pointers to a wealth of external resources, including electronic articles available from publishers’ websites, astronomical object information, data catalogs and data sets hosted by external archives. We currently have links to over 13.3 million records maintained by our collaborators. This depth of information has enabled a number of publications (refereed, non-refereed) in fields such as bibliometrics and information science.

Please note that ADS does not hold the copyright for the abstracts and articles, and their use is free for personal use only; open access abstracts and articles may have distinct terms. For more information, please read our page detailing the Terms and Conditions regulating the use of our resources.

The importance of ADS’s role in supporting the scientific community has been recognized by societies and individuals.

Varies by title; generally, 1975 to present.