Perhaps you should try some spelling variations:
"state vectors" » "state vector", "state actors", "state detectors"
"state sectors" » "state sector", "estate sektors", "state reactors"
"estate sector" » "state section"
"state action" » "state reactions", "state actors"

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