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.
Online handbook of chemical and physical data for fields such as environmental science, bio-medical chemistry, organic and inorganic chemistry, materials innovation, geo and astrophysics, and solid-state science. Includes information on chemical names, structures, properties and laboratory safety.