"Fraternities without Brotherhood"
 

A book that I had heard of, but had never seen a copy is "Fraternities without Brotherhood" which is available on archive.org at https://archive.org/details/fraternitieswith008910mbp

It was written in 1955 and deals extensively with the efforts to open all social fraternities and sororities to all students. I very much recommend it as a part of GLO history.