I have seen on an auction site some books for sale relating to the German Navies including a first edition of "Die lauchende Kuh" by Jost Metzler and signed by him.
[www.amershamauctionrooms.co.uk]
Nrs 152 & 153 are the relevant ones to look at if anyone is interested.
Regards
MPC

P.S. Nr 151 might also be of interest as it is 2 books about the 1936 Olympics