This is a catch-all for all unknown authorship and such...
A botanist who had unusual belongings left in the Spider Forest of the Feywild.
The author of "A Guide to the Underdark"
Mordenkainen is a very well-known wizard, in the scholarly sense. Many writings of the world have been authored by him
Author of specialized copy of "The Joy of Extradimensional Spaces"
Author of "Analysis of Divination Spell Extension into the Astral Plane"
The author of the book "The Magic of Stone and the Souls of Mountains"
The author of "This Ore That; Choosing your first Rock Golem"