Perhaps you should try some spelling variations:
"city cooperation theories" » "city cooperation series", "city cooperation theory", "city collaboration theories", "city corporation theories", "china cooperation theories", "city corporations theories"
"mars colonization israel" » "mars communication israel", "mars colonization still", "mars colonization history", "mrsa colonization israel", "jews colonization israel", "pro colonization israel"
"its colonization failed" » "its colonization still", "its organizations failed", "anti colonization failed", "jews colonization failed", "mrsa colonization failed"

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: (("mars colonization israel") or ((("its colonization failed") or ("city cooperation theories"))))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (("mars colonization israel") OR ((("its colonization failed") OR ("city cooperation theories")))).
• Removing quotes may allow a broader search: (( mars colonization israel ) or ((( its colonization failed ) or ( city cooperation theories )))).
• Adding a wildcard symbol may retrieve word variants: (("mars colonization israel") or ((("its colonization failed") or ("city cooperation theories"))))*.