D3's lore books are broken into People, Quest, Bestiary, and World lore book categories, though they are discovered in areas/zones, not by those categories. You'll see the one I'm missing below ("Battlefield Reports"), but I thought it would be more useful to make a full list instead of only asking for the one I need. Where are the Act 3 lore books, and when do they appear?
Best Answer
This forum post includes details on how to find most but not all of the lore books for "Primary Sources", "History of Arreat" and "Espionage".
For the beast lore, I believe it is fairly straightforward to obtain by killing all the new monsters in Act 3, but I will look for a good source. It is difficult to describe their locations since many are randomly generated.