Perhaps you should try some spelling variations:
"proletarian revolution" » "proletaria revolution", "proletarias revolution", "proletariat revolution", "proletarian evolucion"
"proletarian revoluciones" » "proletaria revoluciones", "proletarias revoluciones", "proletariat revoluciones"
"proletarian revolucion" » "proletaria revolucion", "proletarias revolucion", "proletariat revolucion"

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: "((\"proletarian revolution\") OR (((\"proletarian revoluciones\") OR (\"proletarian revolucion\"))))~".
• Removing quotes may allow a broader search: (( proletarian revolution ) OR ((( proletarian revoluciones ) OR ( proletarian revolucion ))))~.
• Adding a wildcard symbol may retrieve word variants: (("proletarian revolution") OR ((("proletarian revoluciones") OR ("proletarian revolucion"))))*.