Perhaps you should try some spelling variations:
vocational disparities » educational disparities, national disparities, regional disparities
higher vocational » higher educational
output gaps » output gap
output has » output phase, output gap, output a
agricultural » agriculture

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

• Performing a fuzzy search may retrieve terms with similar spellings: agricultural ((output has) or (output gaps)) higher vocational disparities.~.
• If you are trying to use Boolean operators, they must be ALL CAPS: agricultural ((output has) OR (output gaps)) higher vocational disparities..
• Adding a wildcard symbol may retrieve word variants: agricultural ((output has) or (output gaps)) higher vocational disparities.*.