Everything from Asimov. The Mars trilogy by Kim Stanley Robinson. The Culture books from Iain Banks. The Rama series from Clarke although it got tiresome after a while. The Sparrow and Children of God from Mary Doria Russell. Contact by Sagan which by the way is one of the very few sci-fi books that were successfully depicted in movies. Brave new world from Huxley. Old one but still highly relevant. The first ones from Gibson. The Enter series by Orson Scott Card. Bradbury's Farhenheit 451. This one is a classic. Revelation Space from Alaistair Reynolds who writes the most hardcore sci-fi I've ever come across.
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