Perhaps you should try some spelling variations:
"de communication issues" » "de community issues", "de communication india", "de communication united", "mobile communication issues", "online communication issues"
"early cooperation studies" » "early cooperation series", "early cooperation sources", "early cooperation implies", "early operation studies", "early cooperative studies", "energy cooperation studies"
"its colonization still" » "its colonization failed", "its colonization israel", "its colonization songs", "anti colonization still", "jews colonization still", "mars colonization still"

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

• The words AND, OR and NOT may confuse the search; try adding quotes: "((\"de communication issues\") OR (((\"early cooperation studies\") OR (\"its colonization still\"))))~".
• Removing quotes may allow a broader search: (( de communication issues ) OR ((( early cooperation studies ) OR ( its colonization still ))))~.
• Adding a wildcard symbol may retrieve word variants: (("de communication issues") OR ((("early cooperation studies") OR ("its colonization still"))))*.