Reference books are encyclopedias, directories, and other similar books designed for east access to information. They are handy and informative, so use them as a starting point for your research. It's a quick way to find out important names and events, get ideas for keywords to use in online searching, and get an overview of your subject.
The Garland Encyclopedia of World Music is one of the most highly regarded music research tools. All the articles are written by scholars with expert knowledge of the topics and edited by other scholars, so you can be sure that you're getting reliable information. The African American Music Reference and Classical Music Reference Library link you to more subject-specific research materials which you can search by keywords.
Reference materials can be great places to go for basic information about your topic. Here are some items available at Library that might be useful for your assignment. Note that these items must be used in the library only.