In your petition cover letter, do not use paragraphs to summarize your reference experts' qualification or reputation. It will make your petition letter lengthy, and those paragraphs in fact may dilute your real points. The qualification of each reference expert should be just highlighted simple and to the point. 

If you still want to say more about your references, you could provide a detailed CV on top of his or her reference letter in the Appendix/Exhibit. If the USCIS adjudicator has time, he or she can still flip through the pages.

Also, the person who writes the reference letter should be well established senior researchers in the fields with high reputation in the field. Only the comments from the independent and highly reputed experts in the field are valuable and convincing to the USCIS adjudicators.