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. The ADS maintains three bibliographic databases containing more than 7.7 million records: Astronomy and Astrophysics, Physics, and arXiv eprints. The main body of data in the ADS consists of bibliographic records, which are searchable through highly customizable query forms, and fulltext scans of much of the astronomical literature which can be browsed or searched via our fulltext search interface. Integrated in its databases, the ADS provides access and pointers to a wealth of external resources, including electronic articles, data catalogs and archives. We currently have links to over 8.3 million records maintained by our collaborators.

Website: http://ads.astro.puc.cl/