I was just looking up locals who had become a chapter of Zeta Tau Alpha, and I found a great website that has the Baird's Directory index. The author of the site actually went back through all the old editions, so the list shows when the organization first showed up in Baird's, and when it was last in Baird's. It also shows if a GLO merged into another one.
I noticed there seemed to be very few GLO's starting with Epsilon, if that helps.
www.iglsa.net/iglsa/bairds.htm
You should be able to pick out a GLO that is no longer, and that did not merge into a national/international GLO.Good luck. I'd love to read the book, too.