Perhaps you should try some spelling variations:
"regional cooperation history" » "regional integration history", "regional corporation history", "regional federation history"
"_ decolonization from" » "_ decolonisation from", "_ decolonization africa", "_ decolonization across"
"its colonization still" » "its colonization failed", "its colonization israel", "its colonization songs", "anti colonization still", "jews colonization still", "mars colonization still"

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

• The words AND, OR and NOT may confuse the search; try adding quotes: "((((\"_ decolonization from\") OR (\"its colonization still\"))) OR (\"regional cooperation history\"))~".
• Removing quotes may allow a broader search: (((( _ decolonization from ) OR ( its colonization still ))) OR ( regional cooperation history ))~.
• Adding a wildcard symbol may retrieve word variants: (((("_ decolonization from") OR ("its colonization still"))) OR ("regional cooperation history"))*.