Est. 1998 — 27 years of woodworking knowledge
No turning back now
Joe in a Cleveland suburb
I glued up this monster over the weekend. Went ok. No drama.
I ended up using TBIII. No epoxy. That stuff is too expensive for me.
Next is making shelves, a top, and molding for around the top. Hope to be done by Christmas. 
P.S. don't check it for squareness...
Gluing up for squarness
Bill Tindall, E.Tn.
What I have found is that well executed joints result in a case coming together square. It has been many pieces since I had to coax one into submission.
However, with you bookcase you have the same problem I had with the flimsy face frame of the corner cupboard. There are not enough joints to bring it square when the joints are snugged. The solution is to add temporary joints. In my case I could pin nail plywood to the inside of the frame which held it square until the glue cured.
Because you are not going to add doors the result will not be a problem. The whole affair will likely be flexible enough that a load of books will settled it onto the likely irregular floor.