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 sources" » "city cooperation series", "city cooperation studies", "city cooperation countries", "city corporation sources", "china cooperation sources", "city corporations sources"
"re colonization still" » "re colonization failed", "re colonization israel", "re colonization songs", "pro colonization still", "_ colonization still", "jews 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 ((("re colonization still") or ("city cooperation sources"))))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (("class communication issues") OR ((("re colonization still") OR ("city cooperation sources")))).
• Removing quotes may allow a broader search: (( class communication issues ) or ((( re colonization still ) or ( city cooperation sources )))).
• Adding a wildcard symbol may retrieve word variants: (("class communication issues") or ((("re colonization still") or ("city cooperation sources"))))*.