Perhaps you should try some spelling variations:
"eu cooperation studies" » "eu cooperation series", "eu cooperation sources", "eu cooperation implies", "et cooperation studies", "2 cooperation studies", "la cooperation studies"
"mars community issues" » "makers community issues", "smart community issues", "als community issues"
"its migration history" » "u.s migration history", "us migration history", "cs migration history"

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: (((("mars community issues") OR ("eu cooperation studies"))) OR ("its migration history"))~.
• Removing quotes may allow a broader search: (((( mars community issues ) or ( eu cooperation studies ))) or ( its migration history ))~.
• Adding a wildcard symbol may retrieve word variants: (((("mars community issues") or ("eu cooperation studies"))) or ("its migration history"))*.