| Springer Verlag, February 8, 2015, cover price $149.00 | About this edition:
The Golden Oldies series of the journal General Relativity and Gravitation reprints key papers in general relativity theory that were published 30 or more years ago and are either hard to obtain or were originally printed in a language other than English.
, titled "The Earth Lords" | Ace Books, December 1, 1988, cover price $3.95 | also contains The Earth Lords
| About this edition:
In a labyrinth hidden below the Caradian border, dwarfish race rules over humans and plots the downfall of humankind, while Bart Dybig, one of the groups captives, plans his escape to the world above