What has the author Roland Harweg written?

It seems you're asking about an author named "Roland Harweg". However, there is no widely recognized author with that name. It's possible that:

* You might have misspelled the name. Please double-check the spelling.

* The author might be less well-known. Could you provide any more context, such as their genre, nationality, or a specific book title?

* The author might be using a pseudonym.

With more information, I might be able to help you find the author you're looking for.