Frederik Pohl

The Last Theorem

The Fifth Science Fiction Megapack

Pythias

The Knights of Arthur

Plague of Pythons

Beyond the Blue Event Horizon

Lost Sci-Fi Books 241 thru 260: Twenty Forgotten Science Fiction Adventures from the Age of Rocketships and Strange Worlds

Science Fiction Grand Masters 6: Legendary Writers, Unforgettable Stories, And The Greatest Voices In Vintage Science Fiction — A Powerful Collection Of Classic Tales From The Science Fiction Grand Masters Who Shaped The Golden Age Of Science Fiction

Time Travel and Nothing But Time Travel 2: Twenty-Three Classic Journeys Through Time Where One Small Change Can Rewrite History

Vintage Sci-Fi 24 - 22 Science Fiction Short Stories from Philip José Farmer, Lester Del Rey, Robert Bloch, Frederik Pohl, Michael Shaara and more: Alien Visitors, Deadly Missions, And Strange Experiments From The Golden Age Of Vintage Science Fiction

The Tunnel Under The World: The Cost of Knowing the Truth

1950s Science Fiction 12 - 23 Science Fiction Short Stories From the 1950s: Alien Encounters, Time Paradoxes, and Human Reckoning