https://www.theoi.com/Nymphe/Dryades.html

Grimm, Jacob. Teutonic Mythology. (J.S. Stalleybrass edition) George Bell & Sons, London, 1883.

Dr. Curran, Bob. Vampires: A Field Guide to the Creatures That Stalk the Night. Weiser, 2005

https://en.wikipedia.org/wiki/Simonside_Dwarfs

http://faeryfolklorist.blogspot.com/2009/05/duergars-of-simonside.html

https://www.icysedgwick.com/simonside-dwarfs/

And of course, the 5th ed Monster Manual