Perhaps you should try some spelling variations:
"clausula de la nacion mas favorecido" » "clausula de la nacion mas favorecida" (Expand Search), "clausula de la nacion mais favorecida" (Expand Search), "clausula de la nacional mas favorecido" (Expand Search)
"clausula de la nacion mas desfavorecidos" » "clausula de la nacional mas desfavorecidos" (Expand Search), "clausula de la nacion mas desaparecidos" (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: (("clausula de la nacion mas favorecido") OR ("clausula de la nacion mas desfavorecidos"))~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((\"clausula de la nacion mas favorecido\") OR (\"clausula de la nacion mas desfavorecidos\"))".
• Removing quotes may allow a broader search: (( clausula de la nacion mas favorecido ) OR ( clausula de la nacion mas desfavorecidos )).
• Adding a wildcard symbol may retrieve word variants: (("clausula de la nacion mas favorecido") OR ("clausula de la nacion mas desfavorecidos"))*.