it just like to say that these things are bugged, the spawn rates are off like hell, i can safely say that after 200 DM runs it never spawns at Zevrim Thornhoof.
Many off the books where empty with no loot in them at all, or disappeared as you looted them.
After quite a few DM runs, I can safely say, you are correct. There’s no spawn at Zevrim Thornhoof. There’s one at Lethendris in DM East, if you’re looking for one. Also one at Alzzin.
I’ve ran into the issue of empty books quite a few times as well, I always assumed someone else looted it beforehand, but that one may very well be a bug.
As Mage i do solo Dire Maul East and the book that is “empty” happen even if you are solo.
This is a deep problem related to loot table on Classic : some mobs doesn’t loot any items sometime, and it happen more on some mobs (example : all Dire Maul mob in East side, Silithus Air Elemental) than others. I don’t know why, I remember back in Vanilla mob doesn’t always loot, but it happen frankly to much in Classic.