Perhaps you should try some spelling variations:
"Teoria do valedor-trabalho" » "Teoria del valedor-trabalho" (Expand Search)
teoria do » teoria da (Expand Search), teoria del (Expand Search)
"Teoria do valor-trabalho" » "Teoria o valor-trabalho" (Expand Search), "Teoria ao valor-trabalho" (Expand Search), "Teoria del valor-trabalho" (Expand Search)
"teoria de valor-trabalho" » "teoria de valores-trabalho" (Expand Search), "teoria el valor-trabalho" (Expand Search)

Try widening your search to All Fields.

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

• Performing a fuzzy search may retrieve terms with similar spellings: (((("Teoria do valor-trabalho") OR ("Teoria do valedor-trabalho"))) OR ("teoria de valor-trabalho"))~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((((\"Teoria do valor-trabalho\") OR (\"Teoria do valedor-trabalho\"))) OR (\"teoria de valor-trabalho\"))".
• Removing quotes may allow a broader search: (((( Teoria do valor-trabalho ) OR ( Teoria do valedor-trabalho ))) OR ( teoria de valor-trabalho )).
• Adding a wildcard symbol may retrieve word variants: (((("Teoria do valor-trabalho") OR ("Teoria do valedor-trabalho"))) OR ("teoria de valor-trabalho"))*.