How can I get more than 200 results from Google Reader's OAuth API?

I can get up to 200 unread items using this:

http://www.google.com/reader/api/0/stream/contents/user/-/state/com.google/reading-list?n=200&xt=user/-/state/com.google/read

But, how can I get the next 200?

(the xt parameter excludes read items)

You'll need to extract the continuation attribute in the response and then make another request with that value as a c query parameter (see http://code.google.com/p/google-reader-api/wiki/ApiStreamContents for details).