It's best to check with your instructor or advisor if you have a specific copyright question. Some basic guidelines to follow when using material you did not create:
Here are some selected resources that focus on navigating copyright law when writing your thesis or capstone project:
Copyright Essentials for Scholarly Work (courtesy of the University of Virginia)
Copyright at American University (has a good FAQ section)
Use the library's thesis approval form to make your work available in TOPCAT, the online database of the library.