Middle-earth
Another example is C. S. Lewis's "Space Trilogy," in which Earth is also called Middle-earth. Lewis's novels are situated at the approximate time of World War II, with the last novel, "That Hideous Strength," taking place in post-war England, and they specifically bring in references to Tolkien's legendarium (at that time largely unpublished) and treats these references as primary fact within Lewis's fiction. Merlin, of King Arthur fame, is treated as a successor to the Atlantis magic found within "Numinor" (Lewis's unintentional misspelling of Númenor), and similarities can also be found in the Quenya name for Númenor, which is "Atalantë," and Lewis specifically references the earth as Middle-earth twice, both in Chapter 13, "They Have Pulled Down Deep Heaven on Their Heads". Lewis's borrowings came directly from Tolkien himself: they were close friends and shared each other's literary creations. Lewis encouraged Tolkien to persevere with his Middle-earth writings.A small selection from the many books about Tolkien and his created world:
Isaac Asimov
Asimov enjoyed the writings of J. R. R. Tolkien, using "The Lord of the Rings" as a plot point in a Black Widowers story. (Tolkien said that he enjoyed Asimov's science fiction.) He acknowledged other writers as superior to himself in talent, saying of Harlan Ellison, "He is (in my opinion) one of the best writers in the world, far more skilled at the art than I am." Asimov disapproved of the New Wave's growing influence, however, stating in 1967 "I want science fiction. I think science fiction isn't really science fiction if it lacks science. And I think the better and truer the science, the better and truer the science fiction". The feelings of friendship and respect between Asimov and Arthur C. Clarke were demonstrated by the so-called "Clarke-Asimov Treaty of Park Avenue", negotiated as they shared a cab in New York. This stated that Asimov was required to insist that Clarke was the best science fiction writer in the world (reserving second-best for himself), while Clarke was required to insist that Asimov was the best science writer in the world (reserving second-best for himself). Thus, the dedication in Clarke's book "Report on Planet Three" (1972) reads: "In accordance with the terms of the Clarke-Asimov treaty, the second-best science writer dedicates this book to the second-best science-fiction writer."