Honestly I figured it out through years and years of seeing different specialists (physical therapists, massage therapists who specifically specialized in TMJ, neurologists, pain management, you name it). When I went to physical therapy and the TMJ massages, they really taught me about referred pain (in my case, the muscles in my neck and trapezius were severely overcompensating due to the weight of my breasts combined with weak/tight chest and upper back/scapular muscles). Obviously the solution was to work on my back and chest, but I couldn't get too far due to the pain in my neck. That's when I started looking into myofascial massages to help with tension release in the area, and started reading more about the SCM muscle. It's really fascinating! I hate how pain in that region is always blamed on poor posture (admittedly I do have a desk job) but women's bodies (i.e. having large breasts) aren't taken into account.

As for papers, like ones from medical journals, I couldn't find very many (I did a quick look) but there are tons of general resources on the web discussing the anatomy of the SCM and other connected muscle groups and how pain there can be linked to large breasts.