The Time Traders by Andre Norton

American scientists are investigating the fact that Russian scientists have discovered how to transport themselves back in time to learn long-forgotten secrets of the past. That is why young Ross Murdock, above average in intelligence but a destructively independent nonconformist, finds himself on a clandestine government project at a secret base in the Arctic. The very qualities that make him a menace in civilized society are valuable traits in a man who must successfully act the part of a merchant trader of the Beaker people during the Bronze Age.

When they are transferred by a time machine to the remote Baltic region where the Russian post is located, Ross and his partner Ashe are swept into a fantastic action-filled adventure involving Russians, superstitious prehistoric men, and the aliens of a lost galactic civilization that demand every ounce of the Americans' courage.

You can view more about this title at the CruGuru website. It is available from Amazon.com and from Lulu.com. ISBN: 978-1-920265-07-6