Perhaps you should try some spelling variations:
"mars communication issues" » "mars community issues", "mars communication india", "mars communication united", "mass communication issues", "mass communications issues", "markets communication issues"
"et cooperation studies" » "et cooperation series", "et cooperation sources", "et cooperation implies", "et cooperations studies", "eu cooperation studies", "2 cooperation studies"
"its federation history" » "its migration history", "les federations history", "_ federation history", "3 federation history"

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

• Performing a fuzzy search may retrieve terms with similar spellings: (((("mars communication issues") or ("et cooperation studies"))) or ("its federation history"))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (((("mars communication issues") OR ("et cooperation studies"))) OR ("its federation history"))*.
• Removing quotes may allow a broader search: (((( mars communication issues ) or ( et cooperation studies ))) or ( its federation history ))*.