I know about Rork and i'm a great fan too! I've found a website about him and his works and i even own a little booklet-biography with some interviews and rare works.
You can read more about Rork, interviews with Andreas, and find some other publications like 'Cromwell Stone' on these pages:
[link] (in English)
A website with a lot of pictures,
even unpublished ones is this very good fanpage:
[link] (in French...
but just click on the links to find out more if you don't understand all you read)
See you around!