We recommend following the best practices for attribution on the Creative Commons wiki. These are appropriate for providing attribution on Creative Commons-licensed content, and they can also be adapted for use with other content. As best practices, they are flexible and can work with a variety of academic style guides.
Note that U.S. copyright law does not require attribution for most works. However, the Creative Commons licenses all require attribution as a condition of the license. In addition, providing attribution will help your readers identify third-party content and understand their rights and obligations regarding it. It will also help colleagues who may need to edit or build on your work in the future.