The library has several online databases for students to use for this type of paper. The best one to start for controversial issues is Opposing Viewpoints In Context, which offers informed views that present an overview and articles on each side of an issue (these could be from a variety of sources including academic journals, national newspapers and magazines). A similar Pro/Con database is Points of View Reference Source. If you're in the Library A-Z Databases list, the subject Current Events & Issues list those as well as newspaper and magazines that would have the newest articles on many topics.
The library's Writing and Citing LibGuide (especially the Essay section) provides additional guidance for students in writing a persuasive paper.
See the short videos below for demos showing how to do research for a persuasive essay.