Perhaps you should try some spelling variations:
"populists populism" » "populists populists", "populist populist", "populism populist"
"populism populisms" » "populism populist", "populismus populismus", "populists populists"
"popular populism" » "popular royalism", "populism populist", "populist populist"

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: (((("popular populism") OR ("populists populism"))) OR ("populism populisms")).
• The words AND, OR and NOT may confuse the search; try adding quotes: "((((\"popular populism\") OR (\"populists populism\"))) or (\"populism populisms\"))".
• Removing quotes may allow a broader search: (((( popular populism ) OR ( populists populism ))) or ( populism populisms )).
• Adding a wildcard symbol may retrieve word variants: (((("popular populism") OR ("populists populism"))) or ("populism populisms"))*.