Perhaps you should try some spelling variations:
"agricultural reproduction" » "agricultural production", "agricultural productions", "sociocultural reproduction"
"agricultural introduction" » "agriculture introduction", "agricultural production", "agricultural instruction"

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