Perhaps you should try some spelling variations:
22internationales congress » international congress, internationaler kongress, internationalen kongress
internationales congres » international congres, internationaler kongress, internationalen kongress

You may be able to get more results by adjusting your search query.

• If you are trying to use Boolean operators, they must be ALL CAPS: %((22internationales congress) OR (internationales congres)) of mathematicians%22.
• Adding a wildcard symbol may retrieve word variants: %((22internationales congress) or (internationales congres)) of mathematicians%22*.