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place in post-war England, and they specifically bring in references to Tolkien's legendarium (at that time largely unpublished) and treats these references as primary fact within Lewis's fiction.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:
Malvern Hills
J.R.R. Tolkien found inspiration in the Malvern landscape which he had viewed from his childhood home in Birmingham and his brother Hilary's home near Evesham. He was introduced to the area by C. S. Lewis, who had brought him here to meet George Sayer, the Head of English at Malvern College. Sayer had been a student of Lewis, and became his biographer, and together with them Tolkien would walk the Malvern Hills. Recordings of Tolkien reading excerpts from "The Hobbit" and "The Lord of the Rings" were made in Malvern in 1952, at the home of George Sayer. The recordings were later issued on long-playing gramophone records. In the liner notes for "J.R.R. Tolkien Reads and Sings his The Hobbit & The Fellowship of the Ring", George Sayer wrote that Tolkien would relive the book as they walked and compared parts of the Malvern Hills to the White Mountains of Gondor.