7 public-domain matches

Fiction Science Fiction Space Opera

Cover of The Master Mind of Mars

The Master Mind of Mars

Edgar Rice Burroughs

Cover of The Chessmen of Mars

The Chessmen of Mars

Edgar Rice Burroughs

Cover of The warlord of Mars #3

The warlord of Mars #3

Edgar Rice Burroughs

Cover of The Gods of Mars

The Gods of Mars

Edgar Rice Burroughs

Cover of paq'balth: The Klingon Epic

paq'balth: The Klingon Epic

Unknown author

Cover of paq'batlh

paq'batlh

Unknown author

Cover of US-Fantasy 1977–1987

US-Fantasy 1977–1987

Tobias Haupts