The U.S. Geological Survey provides the Nation with reliable, impartial information to describe and understand the Earth. The site includes a dictionary of biology and chemistry terms and a directory of internet resources. Selected articles from the current issue of Science are available for free as well as news articles and professional resources. Past issues can be searched but are only available to subscribers. The table of contents and summaries for the last four issues, a news section, and a downloadable index are available to registered users.
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Special web-only articles and features are open to all. Back issues can be searched but text is only available to subscribers.