Astrophysics Data System (ADS)
The Astrophysics Data System (ADS) is a portal searching three bibliographic databases containing more than 11 million records. Separate search forms are available for Astronomy and Astrophysics, Physics and Geophysics, and the large physics preprint archive named arXiv. Use the new ADS Labs interface to search across abstracts and full-text of the entire data system. A set of browsable interfaces are also available
Help pages and FAQ's are available on-line.
ADS also maintains an extensive citation database. Each record has a count of and link to all the citing (newer) papers. The myADS Update Service is a free custom notification service promoting current awareness of the recent technical literature. ADS is operated by the Smithsonian Astrophysical Observatory (SAO) under a NASA grant.
Please note that all abstracts and articles in the ADS are copyrighted by the publisher, and their use is free for personal use only. For more information, please read their page detailing the Terms and Conditions regulating the use of their resources.
1573 to present, not comprehensive for older years.