Worldwide chemical information available in the form of journals, patents, and books (handbooks, dictionaries, encyclopedias, reports of conferences and symposia, review volumes, research treatises, and textbooks). The output of journal articles has increased almost exponentially in the last 70 years. Of major importance in making this information explosion available to scientists are the abstract journals, particularly Chemical Abstracts, described in Appendix II. Outstanding among periodicals is the Journal of the American Chemical Society, in which more than 2000 articles appear yearly. Hundreds of other journals throughout the world add to the vast stream of chemical literature. In book form, there are four monumental multivolume compendia (the dates are for the original edition, but in most cases there have been several revisions): Abegg and Gmelin's Handbuch der Anorganischen Chemie (1870), Beilstein's Handbuch der Organischen Chemie (1881), Mellor's Inorganic and Theoretical Chemistry (1922), and Heilbron's Dictionary of Organic Compounds(approximately 1920). Other noteworthy reference sources are Merck Index (1889), Handbook of Chemistry and Physics (1918), Lange's Handbook of Chemistry (1934), Chemical Engineers Handbook (1934), Ring Index (1940), Hackh's Chemical Dictionary (1929), and Kirk-Othmer's Encyclopedia of Chemical Technology (1947). The ACS Monograph Series, established in 1919, is devoted to high-level treatises in developing areas of chemistry. Many useful series of “Advances,” reviewing progress in specific fields, have appeared from time to time. Many of these publications are available for computerized information retrieval.See Chemical Education.