Perhaps you should try some spelling variations:
"seis estudios peruanoss." » "seis estudios peruanos.", "los estudios peruanoss.", "dos estudios peruanoss.", "dios estudios peruanoss."
"series estudios urbanos." » "serie estudios urbanos.", "tres estudios urbanos.", "leyes estudios urbanos.", "series estudio urbanos.", "series estudios peruanoss.", "series estudios hispanos."
"seis estudios urbano." » "seis estudio urbano.", "seis estudios peruanos.", "seis estudios hispano.", "los estudios urbano.", "dos estudios urbano.", "dios estudios urbano."

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

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