Perhaps you should try some spelling variations:
"city cooperation studies" » "city cooperation series", "city cooperation sources", "city cooperation implies", "city corporation studies", "china cooperation studies", "city corporations studies"
"its cooperation history" » "its corporation history", "its federation history", "et cooperation history", "its operation history"
"jews colonization _" » "its colonization _", "mars colonization _", "re colonization _"

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