Perhaps you should try some spelling variations:
"teoria do valor-trabalho" » "teoria da valor-trabalho" (Expand Search), "teoria del valor-trabalho" (Expand Search), "teoria o valor-trabalho" (Expand Search), "teoria ao valor-trabalho" (Expand Search), "teoria do valedor-trabalho" (Expand Search)
"Teoria de valor-trabalho" » "Teoria el valor-trabalho" (Expand Search)
"Teoria de valores-trabalho" » "Teoria el valores-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 de valor-trabalho") OR ("Teoria de valores-trabalho"))))~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((\"teoria do valor-trabalho\") OR (((\"Teoria de valor-trabalho\") OR (\"Teoria de valores-trabalho\"))))".
• Removing quotes may allow a broader search: (( teoria do valor-trabalho ) OR ((( Teoria de valor-trabalho ) OR ( Teoria de valores-trabalho )))).
• Adding a wildcard symbol may retrieve word variants: (("teoria do valor-trabalho") OR ((("Teoria de valor-trabalho") OR ("Teoria de valores-trabalho"))))*.