Perhaps you should try some spelling variations:
integration theories » integration theorems, integrationstheorie 2, integration theory
irrigation scheme » irrigation systems
syria irrigation » africa irrigation, drip irrigation, surge irrigation
support syria » support social, support agri
support grid » support agri, support grant, support group

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

• Performing a fuzzy search may retrieve terms with similar spellings: (( support syria irrigation scheme. ) or ( support grid integration theories. ))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (( support syria irrigation scheme. ) OR ( support grid integration theories. )).
• Adding a wildcard symbol may retrieve word variants: (( support syria irrigation scheme. ) or ( support grid integration theories. ))*.