In most cases, if you link to a work available online you will not need to ask for permission.
In the Library databases, most materials include a permalink or persistent link that you can use in Moodle or your course syllabus. You can link to articles, ebooks, ebook chapters, and streaming video.
...is a limitation on the exclusive rights of the copyright holder. Detailed in Section 107 of U.S. Copyright Law, fair use encourages the use of a copyrighted work without seeking permission from the copyright holder for the purposes of criticism, comment, news reporting, teaching (including multiple copies for classroom use), scholarship, or research. Four factors must be weighed for each instance in which a copyrighted work may be used. The four factors include the following:
Non-profit, educational use of a work is more in favor of fair use than for profit, commercial use of a work.
Using factual works is considered more fair than using highly creative works.
Using small amounts of a work is more fair than using larger amounts or the "heart" of the work.
Do the first three factors indicate that there is an effect on the market for the work?
Fair Use Checklist: Use the Fair Use Checklist from Columbia University to determine whether or not the use of a copyrighted work is fair.
Fair Use Evaluator: Determine if a use is a fair one and document your decisions.