If you are not sure if the sources you are using are acceptable, contact your instructor during their office hours and ask them to take a look at what you have found so far.
If you are heading down the wrong road, this can save you many hours of redoing your research!
There are numerous controversial or pro/con topics to choose from. Some examples are:
For your Persuasive Speech, you will need resources that defend your perspective from a scholarly point of view. Evidence is more important than opinion.
Many of the links under the "General Resources" tab will be useful, but here are some in particular that will contain scholarly information for your persuasive speech. Opposing Viewpoints is especially helpful.
Google Scholar is also very useful for identifying the number of citations each article/book received. Click the number of citations to see those actual citations. That's a great way to find new material that might be related but not have your keywords.