This ist a Reverse-Wherigo-Mystery. Search the 3 numbers and use the Reverse-Wherigo (http://www.wherigo.com/cartridge/details.aspx?CGUID=dcdcd2ff-c171-4487-93bc-678f6d03ac4f). You have to play it overground. If you have the coordinates: use the Checker:
You don't know where Friedrich is and how to get there? Then don't try to log this cache!
Otherwise solve this Reverse-Wherigo-Mystery, use the checker and go to Friedrich, at the end of Friedrich you see this on the right side:
Here go left: go to the end and see "Friedrichs Vesper-Stüble".
This cache can only be done from 1. April to 31. October! All logs between 1. November and 31. March will be deleted!