GeoRefGeoref, published by the American Geological Institute, is one of the principal indexes of geology and related sciences. Georef covers North American geology back to 1669 and world geology since 1933. It indexes journal articles, books, technical reports, dissertations, and other publications. It currently indexes over 3,500 journals, adding 4,000-7,000 records per month. Access is also available to "Georef in Process", covering the very latest in the geological literature in brief form.