NASA astrophysics data system
A NASA-funded project which maintains four bibliographic databases containing more than 4.0 million records: Astronomy and Astrophysics, Instrumentation, Physics and Geophysics, and preprints in Astronomy. The main body of data in the ADS consists of bibliographic records and abstracts of articles and monographs which are searchable and full-text scans of much of the astronomical literature which can be browsed. The databases cover all the major journals, many minor journals, conference proceedings, several observatory reports and newsletters, many NASA reports, and PhD theses. In addition to its databases, the ADS provides access to scanned images of articles from most of the major and most smaller astronomical journals, as well as several conference proceedings series and points to a wealth of external resources, including electronic articles, data catalogs and archives.