The American Heritage® Dictionary of the English Language, Fourth Edition.
Copyright © 2000 by Houghton Mifflin Company. Published by the Houghton Mifflin Company. All rights reserved.
Indo-European and the Indo-Europeans
Calvert Watkins, in the
American Heritage Dictionary of the English Language
Everything You Ever Wanted to Know about Proto Indo-European
Indo-European Documentation Centre
(University of Texas at Austin)
Indo-European Language Demonstration and Exploration Website
Indo-European language tree
Words for"knowing" in the Indo-European Language
The Indo-European Etymological Dictionary