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