Perhaps you should try some spelling variations:
"state actions" » "state action", "state reactions", "state actors"
"state vectors" » "state vector", "state actors", "state detectors"
"state actor" » "state actors", "state action", "state vector"

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: (("state actor") OR ((("state actions") OR ("state vectors")))).
• Removing quotes may allow a broader search: (( state actor ) or ((( state actions ) or ( state vectors )))).
• Adding a wildcard symbol may retrieve word variants: (("state actor") or ((("state actions") or ("state vectors"))))*.