Annotated bibliographies can work wonders for a paper. An annotated bib is a reference for a source followed by a short paragraph describing the source and how it interrelates to other sources you’ve selected. You can find an in depth guide to writing annotations here: How to Write an Annotated Bibliography.
Now, do that for every source you think you might use (even if it’s more than the minimum). This way, you can see how they work together. Or not. You’ll often find that you can eliminate more articles from your group of sources after writing an annotated bib.
Another cool side effect is that the sources you select will be the most relevant and important sources you collected. It may also show you gaps you need to fill!