The Time Traders

The Time Traders, by Andre Norton, is the first volume of a series of related time- and space-travel stories and part of Norton's "Forerunner" universe. Volumes in this sequence are:

• The Time Traders (1958)
• Galactic Derelict (1959)
• The Defiant Agents (1962)
• Key Out of Time (1963)
• Firehand (1994) (written with Pauline M Griffin)
• Echoes in Time (1999) (with Sherwood Smith)
• Atlantis Endgame (2002) (with Sherwood Smith)

Sherwood Smith's collaborative volumes are more polished than Norton's solo work, while retaining the feel of the classic entries in the series.

Project Gutenberg has some examples from this series:

• The Time Traders
• Key Out of Time

LibriVox has an audio book version:

• The Time Traders