Im looking for a general history on World War I, preferably a multivolume. If you know any good single volumes, that is fine, I already own John Keegan's "The First World War" and have already been recommended "The Great War: A Combat History of the First World War" by Peter Hart
Only the first volume has been published, but Hugh Strachan’s history of the First World War is likely to be the definitive multi-volume work. The first volume To Arms is already pretty much definitive for the period covered.
I’ve heard good things about his single volume, but haven’t read it.
It’s organized by topic rather than narratively but there’s also the multi volume Cambridge History of the First World War.