An e-print (electronic preprint) service in the fields of physics (including astrophysics), mathematics, non-linear science, computer science, quantitative biology and statistics.
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 cooperative agreement. The ADS maintains more than 8.7 million bibliographic records and full-text scans of astronomical literature.
Citation database with multidisciplinary coverage of journals in the sciences, social sciences, and arts and humanities. Indexes the journal literature and tracks article citation histories.