• 4 Interplanetary voyages
• 3 Prefect, Ford
• 2 Artificial intelligence
• 2 Dent, Arthur (Fictitious character)
• 2 Human-alien encounters
• 2 Imaginary wars and battles
• 2 Life on other planets
• 2 Scientists
• 2 Time travel
• 2 Utopias
• 1 Astronauts
• 1 Astronomers
• 1 Books
• 1 Citizen participation
• 1 Colonists
• 1 Colonization
• 1 Communicable diseases
• 1 Computer simulation
• 1 Computers and civilization
• 1 Core
• 1 Dent, Arthur
• 1 Digitization
• 1 Effect of human beings on
• 1 End of the world
• 1 Environmental protection

• 4 Izquierdo, Maritza
• 3 Clarke, Arthur C. (Arthur Charles), 1917-2008
• 3 Lem, Stanisław
• 3 Verne, Jules, 1828-1905
• 3 Wells, H. G. (Herbert George), 1866-1946
• 2 Adams, Douglas, 1952-2001
• 2 Barby, Ralph
• 2 Garland, Curtis, 1929-2013
• 2 Gómez Ibáñez, Benito
• 2 López, Norma B. de
• 2 Orzechowska, Joanna
• 2 Pérez Vivas, Alberto
• 2 Zilli, Edith
• 1 Alou, Damián, 1959-
• 1 Ammaniti, Niccolò, 1966-
• 1 Ardila Camberos, Eduar Zamir, 1989-
• 1 Artacho Martín, Lola
• 1 Asimov, Isaac, 1920-1992
• 1 Banham, Lucille
• 1 Baquero, Miguel
• 1 Bellamy, Edward, 1850-1898
• 1 Bernardo, Elena
• 1 Besa, Luis, 1965-
• 1 Bierce, Ambrose, 1842-1914?

• 54 Spanish
• 2 English

• 2 Earth (Planet)
• 2 Mars (Planet)
• 2 Moon
• 1 Boston (Mass.)
• 1 Easter Island
• 1 Florence (Italy)
• 1 London (England)
• 1 Sicily (Italy)

• 28 Fiction
• 7 Short stories
• 4 Humorous fiction
• 2 Apocalyptic fiction
• 2 Detective and mystery fiction
• 2 Dystopian fiction
• 2 Novels
• 2 Psychological fiction
• 1 Action and adventure fiction
• 1 Fables
• 1 Political fiction
• 1 Romance fiction
• 1 Spy fiction
• 1 Utopian fiction
• 1 War fiction

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