Perhaps you should try some spelling variations:
"agricultural transformation" » "cultural transformation", "agricultural information", "structural transformation"
"agriculture introduction" » "agriculture production", "agriculture information", "agricultural productions"
"agricultural production" » "agricultural reproduction"

Try widening your search to All Fields.

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: (("agricultural production") OR ((("agriculture introduction") OR ("agricultural transformation")))).
• Removing quotes may allow a broader search: (( agricultural production ) or ((( agriculture introduction ) or ( agricultural transformation )))).
• Adding a wildcard symbol may retrieve word variants: (("agricultural production") or ((("agriculture introduction") or ("agricultural transformation"))))*.