@@ 181,6 181,8 @@ who make our world a better place.
 
 # /This is the [[https://freenetproject.org][Freenet]] exclusive ebook. If you got it via other channels, please install [[https://freenetproject.org][Freenet]] and share it there! \\ https://freenetproject.org \\ when free speech dies we need a place to organise!/
 
+/This is the free preview-version. If you enjoy this book, please consider buying py2guile from [[http://draketo.de/py2guile][draketo.de/py2guile]] as ebook or printed (ISBN: 9783737568401)./
+
 # /This is the paid digital version -- that’s awesome! Thank you for buying py2guile and supporting Free Culture!/
 
 # /You can download the digital companion to your book from http://draketo.de/dl/4c043c26-py2guile-rev1-dc.zip/