Rick,
Some really good reference books on the DRI are:
"Fokker Dr. I Triplane: A World War One Legend" by Paul Leaman
2003 Classic Publications, or Ian Allan Publishing
"Fokker Dr. I in Action"
Aircraft number 98 Squadron/Signal publications
Both are available from http://www.squadron.com
The first book is a little expensive but is a REALLY nice ref. book on the Dr. I
Dave