Perhaps you should try some spelling variations:
"re democratization africa" » "re democratization china", "re democratization mexico", "re decolonization africa", "_ democratization africa", "13 democratization africa", "2 democratization africa"
"_ communication united" » "_ telecommunication united"
"mars cooperation history" » "mars corporation history", "mars federation history", "early cooperation history", "area cooperation history", "arab cooperation history"

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: (((("re democratization africa") OR ("_ communication united"))) OR ("mars cooperation history"))~.
• Removing quotes may allow a broader search: (((( re democratization africa ) or ( _ communication united ))) or ( mars cooperation history ))~.
• Adding a wildcard symbol may retrieve word variants: (((("re democratization africa") or ("_ communication united"))) or ("mars cooperation history"))*.