Section 107 of the Copyright Law (Title 17) sets forth certain limitations to the exclusive rights of copyright holders. These limitations are called "fair use." To determine if a use of a work qualifies as fair use, four factors must be considered:
If a work is not in the public domain, and you do not in good faith believe your use qualifies for the fair use exemption, you may either chose not to use the material, or you may wish to seek permission to use the work. The copyright holder may charge a fee for that permission. The Copyright Clearance Center is a useful central clearinghouse for granting permissions across a wide variety of sources. Or you may contact the author/copyright holder directly.