Ann Lee Bressler's The Universalist Movement in America is an important resource in understanding Universalist history -- and it's incredibly expensive. A hard copy is now $90. (I got a reader's copy ages ago.)
The good news is that you can read a "Free sample" -- the introduction and chapter one; which are incredibly important -- in Google Play, to help you decide if you want to buy the epub ($68!) or rent it ($34!) … or read it at a theological library.