Perhaps you should try some spelling variations:
decolonisation » colonization, decolonization
colonisation » colonization
decolonization » colonization
decarbonisation » decarbonization

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: (((decolonisation OR colonisation) OR decolonization) OR decarbonisation) of africa.
• The words AND, OR and NOT may confuse the search; try adding quotes: "(((decolonisation OR colonisation) or decolonization) or decarbonisation) of africa".
• Adding a wildcard symbol may retrieve word variants: (((decolonisation OR colonisation) or decolonization) or decarbonisation) of africa*.