The ongoing dispute over file-sharing papers

Here is a very interesting article in German on the controversy surrounding Stan Liebowitz, Felix Oberholzer-Gee, and Koleman Strumpf and the issue of whether illegal file-sharing has hurt music sales.  An English translation is here; Craig Newmark reports as well.  The upshot is that Liebowitz has been attacking the Oberholzer-Gee and Strumpf claim that illegal downloads do not much hurt music sales.  Liebowitz claims that the original paper, published in the JPE, is incorrect.  In English, here is Liebowitz’s side of the story.  Here are our earlier posts on the Oberholzer-Gee/Strumpf paper.  Here are quotations by Koleman Strumpf.  Does anyone have a link to a further defense by the paper’s authors?