Perhaps you should try some spelling variations:
"state sectors" » "state sector", "estate sektors", "state reactors"
"state vectors" » "state detectors"
"state actor" » "state action", "state sector", "state after"
"state actors" » "state actions", "state sectors", "state afters", "state factors"

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 vector"))) OR ((((("state actors") OR ("state sectors"))) OR ("state vectors")))).
• The words AND, OR and NOT may confuse the search; try adding quotes: "((((\"state actor\") or (\"state vector\"))) or (((((\"state actors\") OR (\"state sectors\"))) or (\"state vectors\"))))".
• Removing quotes may allow a broader search: (((( state actor ) or ( state vector ))) or ((((( state actors ) OR ( state sectors ))) or ( state vectors )))).
• Adding a wildcard symbol may retrieve word variants: (((("state actor") or ("state vector"))) or ((((("state actors") OR ("state sectors"))) or ("state vectors"))))*.