Books like What Luther Says
Martin Luther
What Luther Says is 1,682 pages, about 30 hours 50 minutes at 250 words a minute.
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How long each takes
Don Quixote 9.7 h 
The Sherlock Holmes Companion 4.3 h 
Brewer's Dictionary of Phrase and Fable 21.2 h 
Oxford Dictionary of Quotations 21.2 h 
… As One Mad with Wine and Other Similes 9.2 h 
General Index to The Collected Works of C. G. Jung 13.5 h Bar height shows length. Estimated at 250 words a minute.