What is the name in German for Kant's book "The critique of pure reason"?

Hi mitts-ga,

Thanks for your question. 

The title of Immanuel Kant's "Critique of Pure Reason" in German is: 
Kritik der reinen Vernunft

Projekt Gutenberg-DE/Immanuel Kant
http://www.gutenberg2000.de/autoren/kant.htm

Exhaustive Bibliography of English Translations of Kant
http://www.hkbu.edu.hk/~ppp/fne/bibl.html

SEARCH STRATEGY:
Google Search: "critique of pure reason" german title
Library of Congress Catalog
http://catalog.loc.gov/
Search: title search on "critique of pure reason" and clicked on
several records, then on the "full record tabs"

I hope this answers your question. If you require additional
information, please ask for clarification before rating my answer and
I'll do my best to assist you.

Regards,
luciaphile-ga