List of Ace SF double titles

Ace Books published 224 science fiction Ace doubles between 1952 and 1973 in dos-a-dos format, and a further 40 between 1974 and 1978 in a more traditional format in which the two books are both the same way up.

Genres and Collectability

Ace published science fiction, mysteries, and westerns, as well as books not in any of these genres. Collectors of these genres have found the Ace doubles an attractive set of books to collect, because of the unusual appearance of the dos-a-dos format. This is particularly true for the science fiction books, for which several bibliographic references have been written (see the References section). The format inspired a further series of sf doubles published by Tor Books between 1988 and 1991, the Tor Double Novels.

Because the dos-a-dos format is part of the attraction for collectors, titles published between 1974 and 1978, which contained two titles by one or two authors but which are not dos-a-dos are not regarded by some collectors as true Ace Doubles. The distinction is up to each collector; the books are included in the list given below, with the difference in format noted.

The list given here gives a date of publication; in all cases this refers to the date of publication by Ace, and not the date of original publication of the novels. The list is complete for science fiction titles. However, D-13, listed in Miscellaneous Ace Doubles, contains one novel, "Cry Plague!" by Theodore S. Drachman, which can be regarded as sf, and some science fiction collectors treat this as the first sf Ace Double, even though the novel on the other side is not sf in any way.

For more information about the history of these titles, see Ace Books, which includes a discussion of the serial numbering conventions used and an explanation of the letter-code system.

D Series

*D-031 "SF" A. E. van Vogt "The World of Null-A" / "The Universe Maker" (1953)
*D-036 "SF" Robert E. Howard "Conan the Conqueror" / Leigh Brackett "The Sword of Rhiannon" (1953)
*D-044 "SF" Donald A. Wollheim (ed.) "The Ultimate Invader and Other Science-Fiction" / Eric Frank Russell "Sentinels From Space" (1954)
*D-053 "SF" Murray Leinster "Gateway to Elsewhere" / A. E. van Vogt "The Weapon Shops of Isher" (1954)
*D-061 "SF" L. Sprague de Camp "Cosmic Manhunt" / Clifford D. Simak "Ring Around The Sun" (1954)
*D-069 "SF" Lewis Padgett (Henry Kuttner and C. L. Moore) "Beyond Earth's Gates" / Andre Norton "Daybreak—2250 A. D." (1954)
*D-073 "SF" Donald A. Wollheim (ed.) "Adventures in the Far Future" / Donald A. Wollheim (ed.) "Tales of Outer Space" (1954)
*D-079 "SF" Francis Rufus Bellamy "Atta" / Murray Leinster "The Brain Stealers" (1954)
*D-084 "SF" Isaac Asimov "The Rebellious Stars" / Roger Dee "An Earth Gone Mad" (1954)
*D-094 "SF" Murray Leinster "The Other Side of Here" / A. E. van Vogt "One Against Eternity" (1955)
*D-096 "SF" Andrew North "The Last Planet" / Alan E. Nourse "A Man Obsessed" (1955)
*D-099 "SF" Robert Moore Williams "Conquest of the Space Sea" / Leigh Brackett "The Galactic Breed" (1955)
*D-103 "SF" Philip K. Dick "Solar Lottery" / Leigh Brackett "The Big Jump" (1955)
*D-110 "SF" Isaac Asimov "The 1,000 Year Plan" / Poul Anderson "No World of Their Own" (1955)
*D-113 "SF" Dwight V. Swain "The Transposed Man" / J. T. McIntosh "One in 300" (1955)
*D-118 "SF" Charles L. Harness "The Paradox Men" / Jack Williamson "Dome Around America" (1955)
*D-121 "SF" Andre Norton "The Stars are Ours!" / Sam Merwin, Jr. "Three Faces of Time" (1955)
*D-139 "SF" Nick Boddie Williams "The Atom Curtain" / Gordon R. Dickson "Alien From Arcturus" (1956)
*D-146 "SF" Lee Correy "Contraband Rocket" / Murray Leinster "The Forgotten Planet" (1956)
*D-150 "SF" Philip K. Dick "The World Jones Made" / Margaret St. Clair "Agent of the Unknown" (1956)
*D-162 "SF" Jerry Sohl "The Mars Monopoly" / R. DeWitt Miller and Anna Hunger "The Man Who Lived Forever", (1956)
*D-164 "SF" Gordon R. Dickson "Mankind on The Run" / Andre Norton "The Crossroads of Time" (1956)
*D-173 "SF" Ray Cummings "The Man Who Mastered Time" / Joseph E. Kelleam "Overlords From Space" (1956)
*D-176 "SF" Thomas Calvert McClary "Three Thousand Years" / Margaret St. Clair "The Green Queen" (1956)
*D-193 "SF" Philip K. Dick "The Man Who Japed" / E. C. Tubb "The Space-Born" (1956)
*D-199 "SF" Poul Anderson "Planet of No Return" / Andre Norton "Star Guard" (1956)
*D-205 "SF" Donald A. Wollheim (ed.) "The Earth in Peril" / Lan Wright "Who Speaks of Conquest?" (1957)
*D-215 "SF" Eric Frank Russell "Three To Conquer" / Robert Moore Williams "Doomsday Eve" (1957)
*D-223 "SF" Robert Silverberg "The 13th Immortal" / James E. Gunn "This Fortress World" (1957)
*D-227 "SF" H. Beam Piper and John J. McGuire "Crisis in 2140" / Cyril Judd "Gunner Cade" (1957)
*D-237 "SF" Robert Silverberg "Master of Life and Death" / James White "The Secret Visitors" (1957)
*D-242 "SF" A. E. van Vogt "Empire of the Atom" / Frank Belknap Long "Space Station 1" (1957)
*D-249 "SF" Philip K. Dick "The Cosmic Puppets" / Andre Norton (as Andrew North) "Sargasso of Space" (1957)
*D-255 "SF" Kenneth Bulmer "City Under the Sea" / Poul Anderson "Star Ways" (1957)
*D-266 "SF" E. C. Tubb "The Mechanical Monarch" / Charles L. Fontenay "Twice Upon A Time" (1958)
*D-277 "SF" Murray Leinster "City on The Moon" / Donald A. Wollheim (ed.) "Men on The Moon" (1958)
*D-286 "SF" Robert Silverberg "Invaders From Earth" / Donald A. Wollheim (as David Grinnell) "Across Time" (1958)
*D-291 "SF" Robert Silverberg (as Calvin M. Knox) "Lest We forget Thee, Earth" / Raymond Z. Gallun "People Minus X" (1958)
*D-295 "SF" Jack Vance "Big Planet" / "The Slaves of The Klau" (1958)
*D-299 "SF" Andre Norton "Star Born" / H. Beam Piper and John J. McGuire "A Planet For Texans" (1958)
*D-303 "SF" Poul Anderson "The Snows of Ganymede" / "War of the Wing-Men" (1958)
*D-311 "SF" Robert Silverberg "Stepsons of Terra" / Lan Wright "A Man Called Destiny" (1958)
*D-315 "SF" Eric Frank Russell "The Space Willies" / "Six Worlds Yonder" (1958)
*D-322 "SF" Robert Moore Williams "The Blue Atom" / "The Void Beyond and Other Stories" (1958)
*D-331 "SF" Kenneth Bulmer "The Secret of Zi" / Ray Cummings "Beyond the Vanishing Point" (1958)
*D-335 "SF" Poul Anderson "The War of Two Worlds" / John Brunner "Threshold of Eternity" (1959)
*D-345 "SF" Andre Norton (as Andrew North) "Plague Ship" / "Voodoo Planet" (1959)
*D-351 "SF" Edmond Hamilton "The Sun Smasher" / Robert Silverberg (as Ivar Jorgenson) "Starhaven" (1959)
*D-358 "SF" Robert Silverberg (as Calvin M. Knox) "The Plot Against Earth" / Milton Lesser "Recruit for Andromeda" (1959)
*D-362 "SF" John Brunner "The 100th Millennium" / Donald A. Wollheim (as David Grinnell) "Edge of Time" (1959)
*D-369 "SF" Brian W. Aldiss "Vanguard From Alpha" / Kenneth Bulmer "The Changeling Worlds" (1959)
*D-375 "SF" Damon Knight "Masters of Evolution" / George O. Smith "Fire in the Heavens" (1959)
*D-381 "SF" Jerry Sohl "One Against Herculum" / Andre Norton "Secret of the Lost Race" (1959)
*D-385 "SF" John Brunner "Echo In The Skull" / Alan E. Nourse "Rocket To Limbo" (1959)
*D-391 "SF" John Brunner "The World Swappers" / A. E. van Vogt "Siege of the Unseen" (1959)
*D-403 "SF" Murray Leinster "The Mutant Weapon" / "The Pirates of Zan" (1959)
*D-407 "SF" Poul Anderson "We Claim These Stars!" / Robert Silverberg "The Planet Killers" (1959)
*D-413 "SF" Harlan Ellison "The Man With Nine Lives" / "A Touch of Infinity" (1959)
*D-421 "SF" Philip K. Dick "Dr. Futurity" / John Brunner "Slavers of Space" (1960)
*D-427 "SF" Robert Moore Williams "World of the Masterminds" / "To the Edge of Time and Other Stories" (1960)
*D-431 "SF" A. E. van Vogt "Earth's Last Fortress" / George O. Smith "Lost in Space" (1960)
*D-437 "SF" Andre Norton "The Sioux Spaceman" / Richard Wilson "And Then The Town Took Off" (1960)
*D-443 "SF" Manly Wade Wellman "The Dark Destroyers" / Brian W. Aldiss "Bow Down to Nul" (1960)
*D-449 "SF" Gordon R. Dickson "The Genetic General" / "Time to Teleport" (1960)
*D-453 "SF" Kenneth Bulmer "The Earth Gods Are Coming" / Margaret St. Clair "The Games of Neith" (1960)
*D-457 "SF" Philip K. Dick "Vulcan's Hammer" / John Brunner "The Skynappers" (1960)
*D-465 "SF" John Brunner "The Atlantic Abomination" / Donald A. Wollheim (as David Grinnell) "The Martian Missile" (1960)
*D-471 "SF" John Brunner "Sanctuary in the Sky" / Jack Sharkey "The Secret Martians" (1960)
*D-479 "SF" Wilson Tucker "To the Tombaugh Station" / Poul Anderson "Earthman Go Home!" (1960)
*D-485 "SF" Robert A. W. Lowndes "The Puzzle Planet" / Lloyd Biggle, Jr. "The Angry Espers" (1961)
*D-491 "SF" Fritz Leiber "The Big Time" / Fritz Leiber "The Mind-Spider and Other Stories" (1961)
*D-497 "SF" John Brunner (as Keith Woodcott) "I Speak For Earth" / Ray Cummings "Wandl The Invader" (1961)
*D-507 "SF" Kenneth Bulmer "Beyond the Silver Sky" / John Brunner "Meeting At Infinity" (1961)
*D-509 "SF" Andre Norton "The Beast Master" / "Star Hunter" (1961)
*D-517 "SF" Clifford Simak "The Trouble With Tycho" / A. Bertram Chandler "Bring Back Yesterday" (1961)

F Series

*F-104 "SF" Kenneth Bulmer "No Man's World" / Poul Anderson "Mayday Orbit" (1961)
*F-108 "SF" G. McDonald Wallis "The Light of Lilith" / Damon Knight "The Sun Saboteurs" (1961)
*F-113 "SF" Charles L. Fontenay "Rebels of The Red Planet" / J. T. McIntosh "200 Hundred Years to Christmas" (1961)
*F-117 "SF" Marion Zimmer Bradley "The Door Through Space" / A. Bertram Chandler "Rendezvous on a Lost World" (1961)
*F-119 "SF" Gordon R. Dickson "Special Delivery" / "Delusion Planet" (1961)
*F-123 "SF" Robert Silverberg "Collision Course" / Leigh Brackett "The Nemesis From Terra" (1961)
*F-127 "SF" Marion Zimmer Bradley"Seven From The Stars" / Keith Laumer "Worlds Of The Imperium" (1962)
*F-129 "SF" William F. Temple "The Automated Goliath" / William F. Temple "The Three Suns Of Amara" (1962)
*F-133 "SF" John Brunner "Secret Agent of Terra" / A. Bertram Chandler "The Rim of Space" (1962)
*F-139 "SF" Poul Anderson "The Makeshift Rocket"/"Un-Man and Other Stories" (1962)
*F-141 "SF" Robert Moore Williams "The Darkness Before Tomorrow" / John Brunner (as Keith Woodcott) "The Ladder In The Sky" (1962)
*F-145 "SF" Robert Silverberg "Next Stop The Stars" / "The Seed of Earth" (1962)
*F-147 "SF" Andre Norton "The Sea Siege" / "The Eye of The Monster" (1962)
*F-149 "SF" Robert Moore Williams "King of the Fourth Planet" / Charles V. de Vet and Katherine MacLean "Cosmic Checkmate" (1962)
*F-153 "SF" Marion Zimmer Bradley "The Sword of Aldones" / "The Planet Savers" (1962)
*F-161 "SF" John Brunner "Times Without Number" / Donald A. Wollheim (as David Grinnel) "Destinies Orbit" (1962)
*F-165 "SF" Philip José Farmer "Cache From Outer Space" / "The Celestial Blueprint" (1962)
*F-173 "SF" James White "Second Ending" / Samuel R. Delany " The Jewels of Aptor" (1962)
*F-177 "SF" Terry Carr "Warlord of Kor" / Robert Moore Williams "The Star Wasps" (1963)
*F-185 "SF" Jack Vance "5 Gold Bands" / "The Dragon Masters" (1963)
*F-187 "SF" Leigh Brackett " Alpha-Centauri or Die" / G. McDonald Wallis "Legend of Lost Earth" (1963)
*F-195 "SF" Robert Silverberg "The Silent Invaders" / William F. Temple "Battle on Venus" (1963)
*F-199 "SF" John Brunner (as Keith Woodcott) "The Psionic Menace" / Samuel R. Delany "Captives of the Flame" (1963)
*F-209 "SF" Ken Bulmer "The Wizard of the Starship Poseidon" / Poul Anderson "Let The Spacemen Beware!" (1963)
*F-215 "SF" John Brunner "Listen! The Stars" / Jane Roberts "The Rebellers" (1963)
*F-223 "SF" Keith Laumer "Envoy to New Worlds" / Robert Moore Williams "Flight From Yesterday" (1963)
*F-227 "SF" John Brunner "Astronauts Musn't Land" / "The Space-Time Juggler" (1963)
*F-237 "SF" A. Bertram Chandler "The Ship From Outside" / "Beyond the Galactic Rim" (1963)
*F-242 "SF" John Brunner "The Rites of Ohe" / "Castaway World" (1963)
*F-249 "SF" L. Sprague de Camp "The Hand of Zei"/"The Search for Zei" (1963)
*F-253 "SF" Robert Silverberg (as Calvin M. Knox) "One of Our Asteroids is Missing" / A. E. van Vogt "The Twisted Men" (1964)
*F-261 "SF" Samuel R. Delany "The Towers of Toron" / Robert Moore Williams "The Lunar Eye" (1964)
*F-265 "SF" Jack Vance "The Houses of Iszm" / "Son of The Tree" (1964)
*F-273 "SF" Marion Zimmer Bradley "Falcons of Narabedla" / "The Dark Intruder" (1964)
*F-275 "SF" Philip E. High "No Truce With Terra" / Murray Leinster "The Duplicators" (1964)
*F-285 "SF" Fritz Leiber "Ships to the Stars" / Ken Bulmer "The Million Year Hunt" (1964)
*F-289 "SF" Ken Bulmer "Demons' World" / Tom Purdom "I Want the Stars" (1964)
*F-299 "SF" John Brunner "Endless Shadow"/ Gardner Fox "The Arsenal of Miracles" (1964)

M Series

*M-101 "SF" Leigh Brackett "The Secret of Sinharat" / "People of the Talisman" (1964)
*M-103 "SF" Fred Saberhagen "The Golden People" / Lan Wright "Exile From Xanadu" (1964)
*M-105 "SF" Margaret St. Clair "Message From the Eocene" / "Three Worlds of Futury" (1964)
*M-107 "SF" A. Bertram Chandler "The Coils of Time" / "Into The Alternate Universe" (1964)
*M-109 "SF" G.C. Edmondson "Stranger Than You Think" / "The Ship That Sailed the Time Stream" (1965)
*M-111 "SF" Edmond Hamilton "Fugitive of the Stars" / Kenneth Bulmer "Land Beyond the Map" (1965)
*M-113 "SF" Damon Knight "Off Center" / "The Rithian Terror" (1965)
*M-115 "SF" John Brunner "The Repairmen of Cyclops" / "Enigma From Tantalus" (1965)
*M-117 "SF" Bruce W. Ronald "Our Man in Space" / Jack Sharkey "Ultimatum in 2050 A.D." (1965)
*M-121 "SF" Emil Petaja "Alpha Yes, Terra No!" / Samuel R. Delany "The Ballad of Beta-2" (1965)
*M-123 "SF" John Brunner "The Altar on Asconel" / Ted White "Android Avenger" (1965)
*M-125 "SF" Jack Vance "Monsters in Orbit" / "The World Between and Other Stories" (1965)
*M-127 "SF" John Rackham "We, The Venusians" / Fred Saberhagen "The Water of Thought" (1965)
*M-129 "SF" A. Bertram Chandler "The Alternate Martians" / A. Bertram Chandler "Empress of Outer Space" (1965)
*M-131 "SF" Kenneth Bulmer "Behold The Stars" / Mack Reynolds "Planetary Agent X" (1965)
*M-133 "SF" A. Bertram Chandler "Space Mercenaries" / Emil Petaja"The Caves of Mars" (1965)
*M-135 "SF" Philip E. High "The Mad Metropolis" / Murray Leinster "Space Captain" (1966)
*M-139 "SF" Samuel R. Delany "Empire Star" / Tom Purdom "The Tree Lord of Imeton" (1966)
*M-141 "SF" Jack Vance "The Brains of Earth" / "The Many Worlds of Magnus Ridolph" (1966)

G Series

*G-574 "SF" Avram Davidson "The Kar-Chee Reign" / Ursula K. Le Guin "Rocannon's World" (1966)
*G-576 "SF" John T. Phillifent (as John Rackham) "Danger From Vega" / Avram Davidson "Clash of Star-Kings" (1966)
*G-580 "SF" Mack Reynolds "Dawnman Planet" / Claude Nunes "Inherit the Earth" (1966)
*G-585 "SF" John W. Campbell "The Planeteers" / "The Ultimate Weapon" (1966)
*G-588 "SF" Lin Carter "The Star Magicians" / John Baxter "The Off-Worlders" (1966)
*G-592 "SF" John T. Phillifent (as John Rackham) "The Beasts of Kohl" / John Brunner "A Planet Of Your Own" (1966)
*G-597 "SF" Ursula K. Le Guin "Planet of Exile" / Thomas M. Disch "Mankind Under the Leash" (1966)
*G-602 "SF" Jack Jardine and Julie Jardine (jointly as Howard L. Cory) "The Mind Monsters" / Philip K. Dick "The Unteleported Man" (1966)
*G-606 "SF" John T. Phillifent (as John Rackham) "Time to Live" / Lin Carter "The Man Without a Planet" (1966)
*G-609 "SF" Philip E. High "Reality Forbidden" / A. Bertram Chandler "Contraband From Otherspace" (1967)
*G-614 "SF" Walt Richmond and Leigh Richmond "Shock Wave" / Frederick L. Shaw, Jr. "Envoy to the Dog Star" (1967)
*G-618 "SF" Emil Petaja "The Stolen Sun" / H. Warner Munn "The Ship From Atlantis" (1967)
*G-623 "SF" Philip E. High "These Savage Futurians" / John T. Phillifent (as John Rackham) "The Double Invaders" (1967)
*G-632 "SF" A. Bertram Chandler "Nebula Alert" / Mack Reynolds "The Rival Rigelians" (1967)

H Series

*H-20 "SF" Kenneth Bulmer "The Key to Irunium" / Alan Schwartz "The Wandering Tellurian" (1967)
*H-21 "SF" Jack Vance "The Last Castle" / Tony Russell Wayman "World Of The Sleeper" (1967)
*H-22 "SF" Tom Purdom "Five Against Arlane" / Emil Petaja "Lord of the Green Planet" (1967)
*H-27 "SF" Juanita Coulson "Crisis on Cheiron" / E. C. Tubb "The Winds of Gath" (1967)
*H-29 "SF" Walt Richmond and Leigh Richmond "The Lost Millennium" / A. Bertram Chandler "The Road to the Rim" (1967)
*H-34 "SF" Mack Reynolds "Computer War" / E. C. Tubb "Death is a Dream" (1967)
*H-36 "SF" Emil Petaja "Tramontane" / Michael Moorcock "The Wrecks Of Time" (1967)
*H-40 "SF" E. C. Tubb "C.O.D. Mars" / John T. Phillifent (as John Rackham) "Alien Sea" (1968)
*H-48 "SF" Ellen Wobig "The Youth Monopoly " / Lan Wright "The Pictures Of Pavanne" (1968)
*H-51 "SF" John M. Faucette "Crown Of Infinity" / Emil Petaja "The Prism" (1968)
*H-56 "SF" Ernest Hill "Pity About Earth" / R. A. Lafferty "Space Chantey" (1968)
*H-59 "SF" Philip E. High "The Time Mercenaries" / Louis Trimble "Anthropol" (1968)
*H-65 "SF" Mack Reynolds "Mercenary From Tomorrow" / Kenneth Bulmer "The Key to Venudine" (1968)
*H-70 "SF" Dean R. Koontz "Star Quest" / Emil Petaja "Doom of the Green Planet" (1968)
*H-77 "SF" Juanita Coulson "The Singing Stones" / E. C. Tubb "Derai" (1968)
*H-85 "SF" Philip E. High "Invader on My Back" / Donald A. Wollheim (as David Grinnell) and Lin Carter "Destination: Saturn" (1968)
*H-91 "SF" Laurence M. Janifer and S.J. Treibich "Target Terra" / John Rackham "The Proxima Project" (1968)
*H-95 "SF" Clifford D. Simak "So Bright the Vision" / Jeff Sutton "The Man Who Saw Tomorrow" (1968)
*H-103 "SF" Mack Reynolds "Code Duello" / John M. Faucette "The Age of Ruin" (1968)

Numbered Series

*22600 "SF" Dean R. Koontz "The Fall Of The Dream Machine" / Kenneth Bulmer "The Star Venturers" (January 1969)
*72400 "SF" A. Bertram Chandler "The Rim Gods" / Laurence M. Janifer "The High Hex" (February 1969)
*30300 "SF" Fritz Leiber "The Green Millennium" / "Night Monsters" (March 1969)
*37250 "SF" Marion Zimmer Bradley "The Brass Dragon" / John T. Phillifent (as John Rackham) "Ipomoea" (April 1969)
*23140 "SF" Dean R. Koontz "Fear That Man" / E. C. Tubb "Toyman" (May 1969)
*77710 "SF" Robert Lory "The Eyes Of Bolsk" / Mack Reynolds "The Space Barbarians" (June 1969)
*81680 "SF" John Jakes "Tonight We Steal The Stars" / Laurence M. Janifer and S. J. Treibich "The Wagered World" (July 1969)
*12140 "SF" Brian M. Stableford "Cradle of the Sea" / Kenneth Bulmer "The Wizards of Senchuria" (August 1969)
*42800 "SF" E. C. Tubb "Kalin"/ Alex Dain "The Bane of Kanthos" (September 1969)
*23775 "SF" Barry N. Malzberg (as K.M. O'Donnell) "Final War and Other Fantasies" / John Rackham "Treasure of Tau Ceti" October 1969)
*42900 "SF" Lin Carter "Tower Of The Medusa" / George H. Smith "Kar Kaballa" (November 1969)
*66160 "SF" Nick Kamin "Earthrim" / Walt Richmond and Leigh Richmond "Phoenix Ship" (December 1969)
*89250 "SF" Marion Zimmer Bradley "The Winds Of Darkover" / John Rackham "The Anything Tree" (January 1970)
*06707 "SF" Brian M. Stableford "The Blind Worm" / Emil Petaja "Seed of the Dreamers" (February 1970)
*81610 "SF" Donald A. Wollheim (as David Grinnell) "To Venus! To Venus!" / E. C. Tubb "The Jester at Scar" (March 1970)
*27235 "SF" Walt Richmond and Leigh Richmond "Gallaghers Glacier" / "Positive Charge" (April 1970)
*24100 "SF" John T. Phillifent (as John Rackham) "Flower of Doradi" / Thomas Edward Renn (as Jeremy Strike) "A Promising Planet" (May 1970)
*76096 "SF" Jeff Sutton "Altons Unguessable" / Kenneth Bulmer "The Ships of Durostorum" (June 1970)
*52180 "SF" Robert Lory "A Harvest Of Hoodwinks" / "Masters Of The Lamp" (July 1970)
*78400 "SF" John Jakes "Mask of Chaos" / Barrington Bayley "The Star Virus" (August 1970)
*51375 "SF" Philip José Farmer "The Mad Goblin" / Philip José Farmer "Lord of the Trees" (September 1970)
*11560 "SF" Suzette Haden Elgin "The Communipaths" / Louis Trimble "The Noblest Experiment" (October 1970)
*13793 "SF" Dean R. Koontz "Soft Come the Dragons" / "Dark of the Woods" (November 1970)
*27400 "SF" Neal Barrett, Jr. "The Gates of Time" / Barry N. Malzberg (as K.M. O'Donnell) "Dwellers of the Deep" (December 1970)
*58880 "SF" Sam Lundwall "Alice's World" / "No Time For Heroes" (January 1971)
*05595 "SF" Kenneth Bulmer "Electric Sword Swallowers" / John T. Phillifent (as John Rackham) "Beyond Capella" (February 1971)
*11182 "SF" Ron Goulart "Clockwork Pirates" / "Ghost Breaker" (March 1971)
*71082 "SF" Claudia Nunes and Rhoda Nunes "Recoil" / E. C. Tubb "Lallia" (April 1971)
*13783 "SF" A. Bertram Chandler "The Dark Dimensions" / "Alternate Orbits" (May 1971)
*13805 "SF" John T. Phillifent (as John Rackham) "Dark Planet" / Robert J. Antonick (as Nick Kamin) "The Herod Men" (June 1971)
*77785 "SF" Eric Frank Russell "Six Worlds Yonder" 6 unrelated stories. / "The Space Willies" A spoof on Scientology. (July 1971)
*68310 "SF" John Glasby "Project Jove" / Kenneth Bulmer "The Hunters of Jundagai" (August 1971)
*27415 "SF" Barry N. Malzberg (as K.M. O'Donnell) "Gather in the Hall of Planets" / "In the Pocket and Other S-F Stories" (September 1971)
*66525 "SF" Will F. Jenkins (as Murray Leinster) "The Mutant Weapon" / "Pirates of Zan" (October 1971)
*75781 "SF" Leigh Brackett "The Secret of Sinharat" / Leigh Brackett "People of the Talisman" (November 1971)
*77525 "SF" Jack Vance "Son of the Tree" / "The Houses of Iszm" (December 1971)
*33710 "SF" Neal Barrett Jr. "Highwood" / Barrington Bayley "Annihilation Factor" (January 1972)
*15890 "SF" A. Bertram Chandler "The Rim of Space" / Marion Zimmer Bradley "The Door Through Space" (February 1972)
*79975 "SF" E. C. Tubb "Technos" / E. C. Tubb "A Scatter of Stardus" (March 1972)
*16640 "SF" Jack Vance "The Dragon Masters" / "5 Gold Bands" (April 1972)
*00990 "SF" Susan K. Putney "Against Arcturus" / Dean R. Koontz "Time Thieves" (May 1972)
*37062 "SF" A. Bertram Chandler "The Inheritors" / "The Gateway to Never" (June 1972)
*10293 "SF" John T. Phillifent (as John Rackham) "Earthstrings" / Ken Bulmer "The Chariots of Ra" (July 1972)
*06612 "SF" Mack Reynolds "Blackman's Burden" / "Border, Breed Nor Birth" (August 1972)
*15697 "SF" Philip K. Dick "The Unteleported Man" / "Dr. Futurity" (September 1972)
*31755 "SF" A. Bertram Chandler "The Hard Way Up" / Robert Lory "The Veiled World" (October 1972)
*11451 "SF" A. Bertram Chandler "Coils of Time" / "Into The Alternate Universe" (November 1972)
*22576 "SF" Marion Zimmer Bradley "Falcons of Narabedla" / "The Dark Intruder & Other Stories" (December 1972)
*76960 "SF" Lester del Rey "Badge of Infamy" / "The Sky is Falling" (January 1973)
*11650 "SF" Mack Reynolds "Computer War" / "Code Duello" (February 1973)
*93900 "SF" Ross Rocklynne "The Sun Destroyers" / Edmond Hamilton "A Yank at Valhalla" (March 1973)
*16641 "SF" Jack Vance "The Dragon Masters" / "The Last Castle" (April 1973)
*53415 "SF" John T. Phillifent "Hierarchies" / Doris Piserchia "Mister Justice" (May 1973)
*76380 "SF" William F. Temple "Battle on Venus" / William F. Temple "The Three Suns of Amara" (June 1973)
*89301 "SF" E. C. Tubb "Derai" / "The Winds of Gath" (July 1973)
*48245 "SF" John T. Phillifent "Life Without Lancelot" / William Barton "Hunting on Kunderer" (August 1973)

Serial number 48245, above, was the last Ace Double published in the dos-a-dos format. The remainder of the books listed in this section contain two novels, but are published in the traditional way with a single cover and the text the same way up throughout the book.
*66995 "SF" Mack Reynolds "The Rival Rigelians" / "Planetary Agent X" (June 1974)
*14250 "SF" Mack Reynolds "Depression Or Bust" / "Dawnman Planet" (September 1974)
*20571 "SF" Samuel R. Delany "The Ballad of Beta-2" / "Empire Star" (October 1975)
*24035 "SF" Mack Reynolds "The Five Way Secret Agent" / "Mercenary from Tomorrow" (November 1974)

The remaining novels do not have complete date information, so they are sorted in numerical order of the serial number. Note that the following are also not in dos-a-dos format.
*01685 "SF" Gordon R. Dickson "Alien Art" / "Arcturus Landing"(June 1981)
*11555 "SF" A. Bertram Chandler "The Commodore at Sea" / "Spartan Planet"(June 1979)
*11556 "SF" A. Bertram Chandler "The Commodore at Sea" / "Spartan Planet" (September 1981)(same cover as 11555-1)
*11705 "SF" Robert Silverberg "Conquerors From the Darkness" / "Master of Life and Death" (July 1979)
*24890 "SF" H. Beam Piper "Four-Day Planet" / "Lone Star Planet" (April 1979)
*24892 "SF" H. Beam Piper "Four-Day Planet" / H. Beam Piper and John J. McGuire "Lone Star Planet" (September 1984)
*37063 "SF" A. Bertram Chandler "The Inheritors" / "The Gateway to Never" (June 1978)
*37064 "SF" A. Bertram Chandler "The Inheritors" / "The Gateway to Never" (September 1981)
*37108 "SF" A. Bertram Chandler "Into the Alternate Universe" / "Contraband From Otherspace" (March 1979)
*37109 "SF" A. Bertram Chandler "Into the Alternate Universe" / "Contraband From Otherspace" (September 1981)
*37130 "SF" Robert Silverberg "Invaders From Earth" / "To Worlds Beyond" (July 1980)
*37365 "SF" Robert E. Howard "The Iron Man" / "The Adventures of Dennis Dorgan"
*49252 "SF" Philip José Farmer "Lord of the Trees" / "The Mad Goblin" (May 1980)
*65874 "SF" Robert Sheckley "The People Trap" / "Mindswap"(August 1981)
*66093 "SF" Walter Ernsting (as Clark Darlton) "The Stolen Spacefleet" / Klaus Mahn (as Kurt Mahr) "Sgt. Robot"
*66094 "SF" Willi Voltz (as William Voltz) "Seeds of Ruin" / K. H. Scheer "Planet Mechanica"
*66095 "SF" Walter Ernsting (as Clark Darlton) "Heritage of the Lizard People" / Klaus Mahn (as Kurt Mahr) "Death's Demand"
*66096 "SF" Kurt Brand "Saboteurs in A-1" / Willi Voltz (as William Voltz) "The Psycho Duel"
*66097 "SF" K. H. Scheer "Savior of the Empire" / Walter Ernsting (as Clark Darlton) "The Shadows Attack"
*66098 "SF" Winfried Scholz (as W.W. Shols) "The Wasp Men Attack" / Ernst Vlcek "Atlan #1: Spider Desert"
*66099 "SF" Klaus Mahn (as Kurt Mahr) "Menace of Atomigeddon" / Walter Ernsting (as Clark Darlton) "Atlan #2: Flight from Tarkihl'
*66121 "SF" Winfried Scholz (as W.W. Shols) "Robot Threat: New York" / Hanns Kneifel (as Hans Kneifel) "Atlan #3: Pale Country Pursuit"
*66128 "SF" K. H. Scheer "Atlan #4: The Crystal Prince" / Walter Ernsting (as Clark Darlton) "Atlan #5: War of the Ghosts"
*67021 "SF" Marion Zimmer Bradley"The Planet Savers" / "The Sword of Aldones" (April 1980)
*67025 "SF" Marion Zimmer Bradley"The Planet Savers" / "The Sword of Aldones" (1983)
*67026 "SF" Marion Zimmer Bradley"The Planet Savers" / "The Sword of Aldones" (August 1985)
*67027 "SF" Marion Zimmer Bradley"The Planet Savers" / "The Sword of Aldones" (1987)
*72401 "SF" A. Bertram Chandler "The Dark Dimension" / "The Rim Gods" (August 1978)
*72402 "SF" A. Bertram Chandler "The Rim of Space" / "The Ship From Outside" (November 1979)
*72403 "SF" A. Bertram Chandler "The Dark Dimension" / "The Rim Gods" (September 1981)
*73100 "SF" A. Bertram Chandler "The Road to the Rim" / "The Hard Way Up" (April 1978)
*73101 "SF" A. Bertram Chandler "The Road to the Rim" / "The Hard Way Up" (1979)
*73102 "SF" A. Bertram Chandler "The Road to the Rim" / "The Hard Way Up" (September 1981)
*73390 "SF" Avram Davidson "The Kar-Chee Reign" / "Rogue Dragon" (March 1979)
*78537 "SF" Robert Sheckley "The Status Civilization" / "" (November 1979)
*81237 "SF" Gordon R. Dickson "Time to Teleport" / "Delusion World" (July 1981)
*86495 "SF" L. Sprague de Camp "The Virgin of Zesh" / "The Tower of Zanid" (February 1983)

References

* [http://people.uncw.edu/smithms/ACE.html Ace Image Library] . Contains images of most covers for the doubles in all genres, as well as many of the single titles.
* [http://www.bookscans.com/ Bookscans] . Contains numerous images of the Ace covers.
*Corrick, James A. "Double Your Pleasure: The Ace SF Double", Gryphon Books, 1989. ISBN 0-936071-13-3. A historical article, followed by a checklist of the SF Doubles, giving prior publication history for the contents of each one.
*Thiessen, J. Grant "Science Fiction Collector #1", Pandora's Books, 1976. Includes Ace Double checklist.
*Thiessen, J. Grant "Science Fiction Collector #2", Pandora's Books, date unknown. Includes errata for checklist in #1.
*Tuck, Donald H. "The Encyclopedia of Science Fiction and Fantasy: Volume 3", Advent: Publishers, Inc., 1982. ISBN 0-911682-26-0. Lists all ACE sf titles, single and double, published through 1968.

The following references have not been seen but cover the Ace Doubles:
*Jaffery, Sheldon "Double Trouble: A Bibliographic Chronicle of Ace Mystery Doubles", Starmont Popular Culture Series no. 11, Borgo Press, 1987. ISBN 1-55742-118-8.
*Jaffery, Sheldon "Double Futures: An Annotated Bibliography of the Ace Science Fiction Doubles", Borgo Press, 1999. ISBN 1-55742-139-0.
*Peters, Harold R. "Science Fiction, Fantasy & Horror in the Ace Letter-Series Editions: A Collector's Notebook", Silver Sun Press, 1996.