Well, a lot of the ones I’d suggest have already been listed, so this is “in addition to”
Unfortunately, a lot of this stuff is out of print (and considering the quality of a lot of stuff in print, that’s a crime). You may have to find a used book shop (getting rare, those), go to an SF convention, or ordrer from a used-book site on-lime.
Short Stories of the 1950s – Short, and usually with a nasty twist at the end. Rod Serling adapted a lot of these (or got the writers to do it) for The Twilight Zone. Writers are Fredric Brown, Robert Sheckley, Theodore Cogswell, William Tenn, Charles Beaumont, Richard Matheson, and others (Beaument and Matheson actualy did write for TZ) Brown also wrote fabulous mysteries - don’t miss The Fabulous Clipjoint. Of his SF and Fantasy, read Martian, Go Home!, The Lights in the Sky are Stars, and What Mad Universe.
Jules Verne and H.G. Wells are widely cited, but underappreciated. Verne suffers from the fact that his early translators (Lewis Mercier especially) butchered hi work, cutting out up to 1/3 o the book and badly translating the rest (“The disagreeable country of South Dakota” is the translation of what should be “The Badlands of South Dakota”). If you can, read Walter James Miller’s The Annotated 20,000 Leagues Uner the SEa or The Annotated From the Earth to the Moon iller also released his own translation of 20,000 Leagues. A New translation of The Mysterious Island recently cam out, too. Look for his more obscure books, too. Ace released several in paperback in the 1960s. As for Wells, read The War of the Worlds, The Invisible Man, The Food of the Gods, and his short stories. If you can find it, The World Set Free features the first description of a nuclear war, with “atomic bombs” dropped from airplanes. Wells wrote this in 1914!
If you can find the series, Ballantine/Del Rey’s The Best of… series is excellent collecting work by obscure authors (Raymond Z. Gallun) and obscure works by well’known authors (Jack Williamson). Williamson, by the way, is almost 100, and has a new book coming out (!) Read his Sinister Barrier, Darker Than You Think, The Humanoids (The new movie “I, Robot” has nothing to do with Asimov’s book, but is virtually a rip-off of “The Humanoids”), and The Legion of Space.
Read Cordwainer Smith! Absolutely uniqe. You can get ost of his stuff by getting The Best of Cordwainer Smith, The Rediscovery of Man (I gues they didn’t want to call it “The Second-Best of Cordwainer Smith”), and Norstrilia from Del REY (Plus Quest o the Three Worlds rom Ace.), or you can get all the stories in one volume plus Norstrilia from NESFA Press.
There’s a lt more, but that’ll hold you for now.

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