Perhaps you should try some spelling variations:
integration theories » integration theorems, integrationstheorie 2, integration theory
immigration policies » immigration policy, migration policy
crowd immigration » around immigration, from immigration, gross immigration
from integration » roma integration, from immigration, from international
supply crowd » supply growth, supply cost

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

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