Reference sources are available in general or subject specific contexts and in print or online formats. 

Examples:

• Encyclopedias
• Dictionaries
• Almanacs
• Glossaries
• Handbooks
• Atlases
• Bibliographies
• Indexes

Reference materials are good starting points for research projects because they can provide:

• background or introductory information on a topic
• terminology or additional keywords to use in further searches
• a bibliography listing other materials on a topic