Reference sources such as specialized encyclopedias (see U.S. History Guide) are secondary or tertiary sources that can help you identify a topic for your research, provide an overview of a specific issue, and suggest other materials which might be useful for your research. They can provide historical context, relevant dates and the names of key individuals related to your topic. Always use the index if one is available and remember to follow the cross-references. For ideas on where to begin, ask at the Reference Desk or check out the Research Guides by Subject.