Perhaps you should try some spelling variations:
"mines and natural resources" » "eines and natural resources", "lines and natural resources", "mines and natural resource", "mines and natural ressource"
"minds and natural resources" » "minds and natural resource", "minds and natural ressource"

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• The words AND, OR and NOT may confuse the search; try adding quotes: "((\"mines and natural resources\") OR (\"minds and natural resources\"))".
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