While the internet sources such as WIkipedia are often your first stop when you are unfamiliar with a topic, academic encyclopedias and dictionaries that the libraries subscribe to can be a better starting point for research for your courses.
These overviews are generally relatively short and easy to read and follow, and it's always a good idea to look at a couple of different sources from different places to get the best picture. In addition to offering reliable and authoritative background information on issues and topics, they can lead you to sources by experts in the field.
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