I can't find any either although they look very similar in style to some of the Yugoslavian stamps of the period.
The one on the left has the word 'Rak' which is the word for 'cancer' in several Slav languages. Check out Delcampe under Yugoslavia>Cancer for some similar stamps.

The stamp on the right is a bit tougher. Google translates 'Spomen Dom' as 'Memorial Hall' & 'prvi' as 'first'. USAOJ-a has references to schools & universities, so are we looking at the First school/uni congress at the memorial hall in Bihac, Bosnia and Herzegovina.
There is a cover on Delcampe bearing one of these
