Major chemical information systems
Chemistry databases

Chemical Abstracts (CA) is the bibliographic repository for the world's chemistry literature. It was created in 1907 by Chemical Abstracts Service (CAS), a department of the American Chemical Society (ACS). Since its inception, CAS has reported nearly twenty million bibliographic references and over thirty million structures. Each year, CAS receives around three million documents, which are filtered according to selection criteria that limit the number of documents reported (around 14,000 per week). These reports are divided into 80 sections covering all aspects of chemistry. Since 1962, one year has covered two (half-yearly) volumes of publication. The volumes comprise 26 weekly issues, alternating between sections 1 to 34 (odd-numbered issues)...