I have worked on a project a while back to try and figure that out. There is no publication that I know of. I based my research mostly from pictures and videos that I can find.

You are correct when WSOP first started, it was by invitation only so it's nothing compared to today.
http://www.chiptalk.net/forum/review-drafting-wiki/60281-world-series-poker-wsop-chip-history-jojong.html