Perhaps you should try some spelling variations:
des theater » des theaters, des theatres, goes theater
das theater » arts theater
der theater » oder theater, oper theater, fur theater
dem theater » im theater

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: (( pen/laura ((des theater) OR (das theater)) art ) OR ( pen/laura ((der theater) OR (dem theater)) part )).
• The words AND, OR and NOT may confuse the search; try adding quotes: "(( pen/laura ((des theater) or (das theater)) art ) or ( pen/laura ((der theater) OR (dem theater)) part ))".
• Adding a wildcard symbol may retrieve word variants: (( pen/laura ((des theater) or (das theater)) art ) or ( pen/laura ((der theater) OR (dem theater)) part ))*.