Encyclopedias are reference sources. Use them to gather background knowledge and broader context for your topic.
Wikipedia is the most widely used encyclopedia on the internet. While it is open sourced, it is still a power tool. You will not be citing wikipedia in your papers. Use it to find keywords and look through the citation list to find articles in library databases
Gale Virtual Reference Library
Through the NU Library, you can access the Gale Virtual Reference Library which is a collection of specialized encyclopedias on various topics taught at NU. library.northwestu.edu/databases (Find the Gale Virtual Reference Library in the alpahbatized list)