Above is "Advice", a letter from a sixteen-year-old John Eric Holmes to Famous Fantastic Mysteries, a fantasy and sci-fi pulp magazine, with many enthusiastic suggestions for older stories they might republish. The letter appeared on page 127 of the April 1946 issue. Many thanks to Michael Calleia for locating this artifact in the Internet Archive!
At the time of writing this letter, Holmes attended the Punahou School in Honolulu where he lived with his parents; his father Wilfred "Jasper" Holmes taught engineering at the University of Hawaii, both before and after WWII. Wilfred had remained on the island during the war, serving as an intelligence officer in the Navy, about which he later wrote a book, Double-Edged Secrets (1979). Wilfred was himself an author of fiction, having written naval adventure stories under the pseudonym Alec Hudson since the '30s, the majority published in the Saturday Evening Post.
According to an interview with John Martin, at the age of eight Eric discovered the works of Edgar Rice Burroughs, and was even able to meet the author at his house in Hawaii and have a Tarzan book signed. And then around the time he turned ten, Eric found "the pulps". The author bio for his short story "Martian Twilight" (1991), states that "he read S. J. Perelman's review of the first issue of CAPTAIN FUTURE in the THE NEW YORKER's "Talk of the Town," [January 1940] and discovered the pulps. He has been a dyed in the wool fan ever since". While most of his recommendations in "Advice" are for "Weird Fiction" authors, he was also a fan of the adventure side of the pulps. His son Chris Holmes relays in "John Eric Holmes - The Books" that "[h]is favorite pulp hero, next to Captain Future, was Doc Savage. He also enjoyed the Shadow, the Spider, the Avenger and Fu Manchu."
Eric would graduate from Punahou the following year (1947), when his yearbook bio noted that he "keeps busy trying to crash the pulp market". Eventually he had a single story, the military sci-fi "Beachhead on the Moon", appear in the pulp Blue Book in 1951, when he was a psychology student at Stanford.
Eric Holmes remained a lifetime fan of these authors. Thirty years after this letter, he would write an authorized sequel to Burroughs' Pellucidar series, Mahars of Pellucidar (1976), as well a further unpublished continuation, Red Axe of Pellucidar. And I've described his role in bringing the Lovecraftian Mythos into D&D in the later '70s. Chris Holmes indicates that [h]e read everyone in the "Lovecraft Circle" and his favorite of Lovecraft's influences were William Hope Hodgson and Arthur Machen". In 1988, while living in the UK, Eric sent a short report describing a meeting of the Machen Society (an appreciation club) to the fanzine Crypt of Cthulhu, published in issue 57.
From this list, we can also see how from an early age Eric Holmes was "primed" to embrace D&D when it appeared in the mid-70's. While only three of the authors he suggests are are also found in Appendix N (Burroughs, Dunsany and Lovecraft, with an earlier version in Dragon also including Blackwood), the majority were strong influences on Lovecraft; all except Burroughs, Collier, Roberts and Taine are mentioned in H.P. Lovecraft's essay Supernatural Horror in Literature.
Authors Recommended for the Pulps by Holmes in 1946, in "Appendix N" format
Burroughs, Edgar Rice
Chambers, Robert W. — THE KING IN YELLOW (1895)
Dunsany, Lord (Edward Plunkett) — TIME AND THE GODS, THE BOOK OF WONDER (1912), THE BLESSING OF PAN (1927)
Hodgson, William Hope
Lovecraft, H.P. — THE DREAM QUEST OF THE UNKNOWN KADATH (composed 1927, first published by Arkham in 1943)
Machen, Arthur — THE GREAT GOD PAN (1894), THE THREE IMPOSTERS (1895, includes "The Novel of the Black Seal" and "Novel of the White Powder"), THE RED HAND (1895), THE HOUSE OF SOULS (1906 compilation, includes "The Shining Pyramid" (1895) and "The White People" (1904))
Roberts, Charles — IN THE MORNING OF TIME (1919)
Smith, Clark Ashton
Taine, John — THE IRON STAR (1930)