Doesn't King do that in Dark Tower?
I think Wizard and Glass includes items from Wizard of Oz and Wolves of the Calla includes items from Harry Potter.
Wizard of Oz is in the public domain, so you could quote from it without obtaining permission. The items from Harry Potter, that would probably be considered homage, but it helps that King knows Rowling and he may have asked her permission to reference his items to her work.