Fritz Leiber: The 64 Square Madhouse

Conspiracy on Callisto

Three Science Fiction Novellas (Unabridged): optional

Double-Cross

Leigh Brackett: Citadel of Lost Ships

Leviathan Wakes: Book 1 of the Expanse (now a Prime Original series)

Clean Break

Let the Ants Try: A twisted tale of Nuclear destruction....and rebirth

Caliban's War: Book 2 of the Expanse (now a Prime Original series)

Ray Cummings: The Flame Breathers

Crypt-City of the Deathless One

Dastardly Criminals in Space (Unabridged): optional

Assignment on Venus

The Knights Of Arthur (Unabridged)

Nemesis Games: Book 5 of the Expanse (now a Prime Original series)

Lost Sci-Fi Books 1 thru 10

Nine Sci-fi Stories (Unabridged): optional

Abaddon's Gate: Book 3 of the Expanse (now a Prime Original series)