Perhaps you should try some spelling variations:
integration theories » integration theory, integration through, integration efforts
grid integration » trade integration, _ integration, data integration
crop irrigation » drip irrigation, scale irrigation, canal irrigation
supply crop » supply crowd, supply curve
supply grid » supply crowd, support grid
systems. » system.

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: (( supply crop irrigation systems. ) OR ( supply grid integration theories. ))~.
• Adding a wildcard symbol may retrieve word variants: (( supply crop irrigation systems. ) or ( supply grid integration theories. ))*.