With open web searching: Investigate the source! Drill down to the "about" section. Who is creating and publishing this information? What is the goal of sharing it? Does the author have expertise in this area?
Primary evidence: Books, scores, recordings, videos, reviews..If MHC doesn't have what you need, we can get it for you! We can borrow it from another library or order it for ours. Don't forget the extra material from recordings and scores- mine the liner notes, introductory text, and any accompanying material.