Perhaps you should try some spelling variations:
"seis estudios peruanos." » "seis estudios americanos.", "seis estudios ensayos.", "seis estudios cervantinos.", "los estudios peruanos.", "dios estudios peruanos.", "pons estudios peruanos."
"series estudioss urbano." » "series estudios urbano.", "serie estudios urbano.", "serie estudio urbano.", "series estudio urbano."
"dos estudios urbanos." » "los estudios urbanos."

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: (("series estudioss urbano.") or ((("dos estudios urbanos.") or ("seis estudios peruanos."))))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (("series estudioss urbano.") OR ((("dos estudios urbanos.") OR ("seis estudios peruanos."))))*.
• Removing quotes may allow a broader search: (( series estudioss urbano. ) or ((( dos estudios urbanos. ) or ( seis estudios peruanos. ))))*.