original question: Which short story of [Cthulhu Mythos] universe has the earliest copyright date?
answer: the case of charles dexter ward
answer type: Short Story.
auxiliary information: The Cthulhu Mythos is a shared fictional universe, based on the work of American horror writer H. P. Lovecraft. The term was first coined by August Derleth, a contemporary correspondent of Lovecraft, who used the name of the creature Cthulhu‚Äîa central figure in Lovecraft literature and the focus of Lovecraft's short story "The Call of Cthulhu" ‚Äîto identify the system of lore employed by Lovecraft and his literary successors. The writer Richard L. Tierney later applied the term "Derleth Mythos" to distinguish between Lovecraft's works and Derleth's later stories. Authors of Lovecraftian horror use elements of the Mythos in an ongoing expansion of the fictional universe.
The short story of [Cthulhu Mythos] universe, created by H.P Lovecraft was first copyrighted when?