Perhaps you should try some spelling variations:
"german aerospace cluster" » "german aerospace system", "emc aerospace cluster", "german space cluster", "global aerospace 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 spark cluster")).
• Removing quotes may allow a broader search: (( german aerospace cluster ) or ( german spark cluster )).
• Adding a wildcard symbol may retrieve word variants: (("german aerospace cluster") or ("german spark cluster"))*.