Perhaps you should try some spelling variations:
delitos contratos » delitos contra (Expand Search), delitos congresos (Expand Search), delitos continuados (Expand Search)
"delitos control del medio ambiente" » "delitos contra del medio ambiente" (Expand Search), "delito contra del medio ambiente" (Expand Search), "delitos conexos del medio ambiente" (Expand Search), "delitos control de medio ambiente" (Expand Search)
"Delitos contratos del medio ambiente" » "Delitos contratos de medio ambiente" (Expand Search)

Try widening your search to All Fields.

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• Performing a fuzzy search may retrieve terms with similar spellings: (("Delitos contratos del medio ambiente") OR ("delitos control del medio ambiente"))~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((\"Delitos contratos del medio ambiente\") OR (\"delitos control del medio ambiente\"))".
• Removing quotes may allow a broader search: (( Delitos contratos del medio ambiente ) OR ( delitos control del medio ambiente )).
• Adding a wildcard symbol may retrieve word variants: (("Delitos contratos del medio ambiente") OR ("delitos control del medio ambiente"))*.