Perhaps you should try some spelling variations:
"serie ensayos juridicos." » "serie ensayos criticos.", "serie ensayo juridicos."
"serie estudio urbano." » "serie estudios urbano.", "serie estudios urbanos.", "serie espacio urbano.", "series estudios urbano.", "serie studia urbano."
"tres estudios historicos." » "otros estudios historicos.", "los estudios historicos.", "dos estudios historicos.", "tres estudios historico.", "tres estudios historica.", "tres estudios historias."

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: (("serie estudio urbano.") or ((("serie ensayos juridicos.") or ("tres estudios historicos."))))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (("serie estudio urbano.") OR ((("serie ensayos juridicos.") OR ("tres estudios historicos.")))).
• Removing quotes may allow a broader search: (( serie estudio urbano. ) or ((( serie ensayos juridicos. ) or ( tres estudios historicos. )))).
• Adding a wildcard symbol may retrieve word variants: (("serie estudio urbano.") or ((("serie ensayos juridicos.") or ("tres estudios historicos."))))*.