Looks to be another fascinating bio from Kurt Braatz's 296 Verlag. The title in German is 'Unbekannte Pflicht' - 'unbekannte Pflicht' is a compulsory category -or discipline - of aerobatic class, which the participants are not given the opportunity to rehearse and in this context is a reference to Wolfrum's post-war career as one of Germany's best aerobatic pilots..the last quarter of the book deals with his post-war experiences. There are page extracts to read at
www.neunundzwanzigsechs.de