Perhaps you should try some spelling variations:
"tres estudios peruanoss." » "tres estudios peruanos.", "otros estudios peruanoss.", "los estudios peruanoss.", "dos estudios peruanoss."
"series estudios urbanos." » "serie estudios urbanos.", "seis estudios urbanos.", "leyes estudios urbanos.", "serie estudioss urbanos.", "senales estudios urbanos."
"series estudio urbano." » "serie estudio urbano.", "serie estudios urbano.", "senales estudio urbano.", "series estudios urbano.", "series espacio urbano."

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

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