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