Perhaps you should try some spelling variations:
"immigrants agricultural labor mexico." » "migrant agricultural labor mexico.", "immigrants cultural labor mexico.", "immigrants agricultural laborers mexico.", "immigrants agricultural law mexico.", "immigrants agricultural actors mexico."
"immigrants agricultural laws mexico." » "migrant agricultural laws mexico.", "immigrants cultural laws mexico.", "immigrants agricultural laborers mexico.", "immigrants agricultural law mexico.", "immigrants agricultural class mexico.", "immigrants agricultural blacks mexico."

Try widening your search to All Fields.

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: (("immigrants agricultural labor mexico.") or ("immigrants agricultural laws mexico."))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (("immigrants agricultural labor mexico.") OR ("immigrants agricultural laws mexico.")).
• Removing quotes may allow a broader search: (( immigrants agricultural labor mexico. ) or ( immigrants agricultural laws mexico. )).
• Adding a wildcard symbol may retrieve word variants: (("immigrants agricultural labor mexico.") or ("immigrants agricultural laws mexico."))*.