And as far as "researched by" goes, the problem is that a good, solid source has the capability of being traced back to its origins, so stating that Tommy researched this doesn't hold much validity, unless the reader recognizes who Tommy is and has some sort of confidence in his level or depth of research. It's always better (IMHO) to show where the research came from, and even better than that to show the sources it was drawn from.
I get it that its not always possible to do so - I have some early research that I did where I couldn't begin to tell you where it came from - but ideally you'd like to be able to show how you got that info so that they can follow a similar path to either prove it or follow up to improve upon it.