Perhaps you should try some spelling variations:
"complementar constrained problemassssatica" » "complementar contained problemassssatica" (Expand Search), "complementar constrained problemasssssatica" (Expand Search)
"complementaridade constraints problema" » "complementaridade constraints problemas" (Expand Search)

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: "((\"complementar constrained problemassssatica\") OR (\"complementaridade constraints problema\"))~".
• Removing quotes may allow a broader search: (( complementar constrained problemassssatica ) OR ( complementaridade constraints problema ))~.
• Adding a wildcard symbol may retrieve word variants: (("complementar constrained problemassssatica") OR ("complementaridade constraints problema"))*.