Kriegsmarine mechanical NCO schooling manuals 1940

Maschinenkunde für den U.O. Lehrgang Wilhelmshaven. Technical schooling manuals for Kriegsmarine NCO mechanics. Published 1940 by the Schiffsmaschinen-Inspektion Wilhelmshaven. One book with the text 80 pages, and other one 94 pages with technical drawings of ship engins etc. Both size 30x21cm. Both with name of the owner on the first page: Maschinen Obergefreiter G.Schmidt. Used but complete condition. Stains on the cover are caused by rusted staples.