I was surprised to learn recently that the Russians had the most deaths in WWI. I have never really learned anything about that front of the war, with most of my knowledge being about the western front. I would appreciate any help in educating myself!
Norman Stone's The Eastern Front: 1914-1917 is one of the best English language books on the topic, even despite its age (it was published in 1975). You'll see it footnoted in a lot of new works, too. Its a bit dry, as Stone gets very detailed with his analysis, but its probably the most comprehensive English language book available.