Resources licensed with a Creative Commons license require attribution.
Check out the CC Attribution Best Practices, install the OpenAttribute browser extension, or use the example attribution below.
(c) Author "Name of Work" [hyperlinked to where you found the work] License [hyperlinked to license]
Check out the image on this page for an example.
Found an image you liked, forgot to cite it, and can't find it again? Try a reverse image search! As long as you have the image, reverse image searches can help you track down creators so that you can properly attribute them.