Perhaps you should try some spelling variations:
"complementarity obtained problemaass" » "complementar obtained problemaass" (Expand Search), "complementarity obtained problemas" (Expand Search), "complementarity obtained problemaaass" (Expand Search), "complementarity obtained problemasaass" (Expand Search)
"complementaridade constraints problem" » "complementaridade constraints problema" (Expand Search), "complementaridade constraints problemas" (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: (("complementarity obtained problemaass") OR ("complementaridade constraints problem"))~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((\"complementarity obtained problemaass\") OR (\"complementaridade constraints problem\"))".
• Removing quotes may allow a broader search: (( complementarity obtained problemaass ) OR ( complementaridade constraints problem )).
• Adding a wildcard symbol may retrieve word variants: (("complementarity obtained problemaass") OR ("complementaridade constraints problem"))*.