Perhaps you should try some spelling variations:
"german aerospace cluster" » "german aerospace system", "emc aerospace cluster", "global aerospace cluster", "german aerosparse cluster", "german aeroface cluster", "german aerospace clustering"
"german space cluster" » "german sparse cluster", "german face cluster", "german space clustering", "bergman space cluster", "german spa cluster", "german stage cluster"
"german spark cluster" » "german spark chapter", "germany sparks cluster", "german spa cluster", "german part cluster"

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: (("german aerospace cluster") OR ((("german space cluster") OR ("german spark cluster"))))*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((\"german aerospace cluster\") or (((\"german space cluster\") OR (\"german spark cluster\"))))*".
• Removing quotes may allow a broader search: (( german aerospace cluster ) or ((( german space cluster ) OR ( german spark cluster ))))*.