Anthony Grafton has a long, excellent review in The New Republic of Timothy Ryback's Hitler's Books, of which he writes "Ryback's reconstruction is accomplished mostly by weaving back and forth among individual books and other records, from Hitler's own writings to contemporaries' memoirs, as he seeks to show us how books shaped one of the twentieth century's most terrible minds. His effort is worthwhile: one finishes this short, packed book with a firmer take on the sort of intellectual--or pseudo-intellectual--who persuaded the best-educated nation in Europe to make war on civilization and try to exterminate the Jews. But deep insights remain elusive."
He adds "Ryback's useful book brings us a little closer to the mind of the monster. But it could have revealed more than it does. Far too often Ryback interrupts his analysis of the books and their contents, printed and handwritten, to tell us about his own adventures in researching them: only a few of these peeps into his workshop clarify the material. Too seldom does he take the opportunities this material offers to penetrate more deeply into Hitler's psyche. ... This book sticks too close to Hitler, in the end, to tell us as much as it could have."
It continues to surprise me a little bit that for all my interest in historical libraries, I have zero desire to read Ryback's book, or study Hitler's collection. Not even a little bit.