Perhaps you should try some spelling variations:
integration theories » integration theorems, integrationstheorie 2, integration theory
migrant integration » market integration
nonlending services » lending services
support migrant » support migrants, support grant, supporting migrants
drug » drugs

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

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