Women computers working at the Harvard College Observatory, circa 1890 (Wikimedia Commons)
Subject encyclopedias, handbooks and companions provide overviews of ideas, people, and events They are a quick way to find out the basic facts and current points of debate. When using an article in an encyclopedia or handbook, always check the bibliography for further reading at the end of the article. It will provide a selective list of the books, articles, and, sometimes, primary sources.