Perhaps you should try some spelling variations:
integration theories » integration theorems, integrationstheorie 2, integration theory
studies irrigation » studies integration, soviet irrigation, studies innovation
irrigation schemes » irrigation scheme, irrigation systems
der integration » zur integration, sector integration
supply studies » supply sides, supply sources
export der » exponat der, export day, export led

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

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