This page is dedicated to generic web addresses where you can find additional info about Oskar Herrfurth. I know I got some. Well, quite a few. If I find anything useful in the future (very likely), I will include it but some items come and go and it's completely impossible to catch each and every postcard available on auction or scan of an old book in one's personal blog. So look at these addresses as a complementary list of resources.
Enjoy!
http://www.abenteuerroman.info/
http://www.goethezeitportal.de/