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"
"jews colonization still" » "jews colonization failed", "jews colonization israel", "jews colonization songs", "its colonization still", "mars colonization still", "re colonization still"

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