Perhaps you should try some spelling variations:
"tres estadios urbano." » "tres estudios urbano.", "tres estudio urbano.", "tres espacios urbanos.", "tres estados urbano.", "de estadios urbano."
"series estudios urbanos." » "serie estudios urbanos.", "seis estudios urbanos.", "tres estudios urbanos."
"otros estudios urbanos." » "los estudios urbanos.", "dos estudios urbanos.", "etnicos 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: (("tres estadios urbano.") or ((("series estudios urbanos.") or ("otros estudios urbanos."))))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (("tres estadios urbano.") OR ((("series estudios urbanos.") OR ("otros estudios urbanos.")))).
• Removing quotes may allow a broader search: (( tres estadios urbano. ) or ((( series estudios urbanos. ) or ( otros estudios urbanos. )))).
• Adding a wildcard symbol may retrieve word variants: (("tres estadios urbano.") or ((("series estudios urbanos.") or ("otros estudios urbanos."))))*.