Perhaps you should try some spelling variations:
"africa colonization history" » "africa communication history", "africa organization history", "africa civilization history", "arrival colonization history", "africa cooperation history"
"city cooperation history" » "city corporation history", "city federation history", "china cooperation history", "city corporations history"
"_ cooperation state" » "_ cooperation scale", "_ operation state", "_ cooperation strategy"

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: (((("africa colonization history") OR ("_ cooperation state"))) OR ("city cooperation history"))~.
• Removing quotes may allow a broader search: (((( africa colonization history ) or ( _ cooperation state ))) or ( city cooperation history ))~.
• Adding a wildcard symbol may retrieve word variants: (((("africa colonization history") or ("_ cooperation state"))) or ("city cooperation history"))*.