Best practices for the use of copyrighted works include:
- Only use works if you have the copyright holder's permission, the works are in the public domain, or the works are "short" excerpts"
- Credit the author and source of all works
- Only include works that are reasonably necessary for the purpose of your use.
It is always recommended to follow the appropriate citation style rules for your discipline to cite any works you use.
If you are using openly licensed works (e.g. public domain, creative commons), always attribute in the format the creator has indicated.