Perhaps you should try some spelling variations:
"agricultural introduction" » "agriculture introduction", "agricultural production", "agricultural instruction"
"agriculture information" » "agricultural information", "agriculture conservation", "agricultural transformation"

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