Perhaps you should try some spelling variations:
"mass communications issues" » "mass communication issues", "mass communications studies", "mass communications costs", "data communications issues", "crisis communications issues"
"eu cooperation sources" » "eu cooperation series", "eu cooperation studies", "eu cooperation countries", "et cooperation sources", "2 cooperation sources", "la cooperation sources"
"_ federation history" » "_ migration history", "_ federalism history", "_ federated 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: (((("mass communications issues") OR ("eu cooperation sources"))) OR ("_ federation history"))~.
• Removing quotes may allow a broader search: (((( mass communications issues ) or ( eu cooperation sources ))) or ( _ federation history ))~.
• Adding a wildcard symbol may retrieve word variants: (((("mass communications issues") or ("eu cooperation sources"))) or ("_ federation history"))*.