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