Analysis of information sources in references of the Wikipedia article "Hard science fiction" in English language version.
hard science fiction ... the term was first used by P. Schuyler Miller in 1957
PROS: Wonderful "hard" sci-fi setting
[...] Reynolds and his team worked tirelessly to imbue every inch of their game with the cool, atmospheric melancholy so dear to hard sci-fi.
Earliest cite: P. Schuyler Miller in Astounding Science Fiction ... he called A Fall of Moondust "hard" science fiction
Soft science fiction, probably a back-formation from Hard Science Fiction)
Earliest cite: P. Schuyler Miller in Astounding Science Fiction ... he called A Fall of Moondust "hard" science fiction