Perhaps you should try some spelling variations:
"class communication issues" » "class community issues", "class communication india", "class communication united", "mass communication issues", "plans communication issues", "crisis communication issues"
"city cooperation studies" » "city cooperation series", "city cooperation sources", "city cooperation implies", "city corporation studies", "china cooperation studies", "city corporations studies"
"its colonization still" » "its colonization failed", "its colonization israel", "its colonization songs", "anti colonization still", "jews colonization still", "mars colonization still"

Try widening your search to All Fields.

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

• Performing a fuzzy search may retrieve terms with similar spellings: (("class communication issues") or ((("its colonization still") or ("city cooperation studies"))))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (("class communication issues") OR ((("its colonization still") OR ("city cooperation studies")))).
• Removing quotes may allow a broader search: (( class communication issues ) or ((( its colonization still ) or ( city cooperation studies )))).
• Adding a wildcard symbol may retrieve word variants: (("class communication issues") or ((("its colonization still") or ("city cooperation studies"))))*.