1954; first appeared as "The Man in the Iron Cap" in Startling, November 1947. Operation: Outer Space, Fantasy Press, 1954. The Forgotten Planet, Ace, 1954. The Other Side of Here, Ace, 1955; first serialized as The Incredible Invasion in Astounding, August - December 1936. The Planet Explorer, Gnome Press; HUGO Award for best novel of the year, 1957. City on the Moon, Avalon, 1957. War with the Gizmos, Fawcett, 1958. Four from Planet 5, Fawcett, 1959; first appeared as "Long Ago, Far Away" in Amazing, September 1959. The Monster from Earth's End, Fawcett, January 1959. The Mutant Weapon, Ace, 1959; first appeared as "Med Service" in Astounding, August 1957. The Pirates of Zan, Ace, 1959; first serialized as The Pirates of Ersatz in Astounding, February - April 1959. Men Into Space, Berkley, 1960; an episodic but original novel, based on the eponymous television series. The Wailing Asteroid, Avon, December 1960. Creatures of the Abyss, Berkley, 1961 (also known as The Listeners). This World is Taboo, Ace, 1961; first appeared as "Pariah Planet" in Amazing, July 1961. Operation Terror, Berkley, 1962. Talents Incorporated, Avon, 1962. The Other Side of Nowhere, Berkley, May 1964; first serialized as Spaceman in Analog, March - April 1964. Time Tunnel, Pyramid, July 1964. The Duplicators, Ace, 1964; first appeared as "Lord of the Uffts" in Worlds of Tomorrow, February 1964. The Greks Bring Gifts, Macfadden, 1964. Invaders of Space, Berkley, December 1964. Tunnel Through Time, Westminster Press, 1966. Space Captain, Ace, 1966; first serialized as Killer Ship in Amazing, October - December. Checkpoint Lambda, Berkley, 1966; first serialized as Stopover in Space in Amazing, June - August 1966. Miners in the Sky, Avon, April 1967. Space Gypsies, Avon, June 1967. The Time Tunnel, Pyramid, January 1967; original promotional novel based on the 1966–1967 U.S television series The Time Tunnel, a very different story than Leinster's 1964 novel of the same name. The Time Tunnel: Timeslip!, Pyramid, July 1967; original novel based on the television series. Land of the Giants, Pyramid, September 1968; original novel based on television series, reinventing the origin story. Land of the Giants 2: The Hot Spot, Pyramid, April 1969; original novel based on the television series. Land of the Giants 3: Unknown Danger, Pyramid, September 1969; original novel based on the television series. Politics, in Amazing Stories, No. 6, June 1932 Western The Gamblin' Kid (as Will F. Jenkins), A. L. Burt,