Perhaps you should try some spelling variations:
"leyes estudios historicos." » "series estudios historicos.", "los estudios historicos.", "tres estudios historicos."
"serie estado urbano." » "serie estudio urbano.", "serie estado cubano.", "serie estudios urbano.", "serie estudos urbano.", "serret estado urbano."
"seis estudios urbanos." » "los estudios urbanos.", "dos estudios urbanos.", "dios estudios urbanos."

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