Perhaps you should try some spelling variations:
"series estudios peruanoss." » "series estudios peruanos.", "series estudios urbanos.", "serie estudios peruanoss.", "leyes estudios peruanoss.", "sociales estudios peruanoss."
"seis estudios peruanoss." » "seis estudios peruanos.", "seis estudios urbanos.", "los estudios peruanoss.", "dos estudios peruanoss.", "dios estudios peruanoss."
"tres estudios urbano." » "tres estudios urbanos.", "tres estudio urbano.", "tres estudios peruanos.", "otros estudios urbano.", "los estudios urbano.", "dos 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 peruanoss.") or ("seis estudios peruanoss."))) or ("tres estudios urbano."))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (((("series estudios peruanoss.") OR ("seis estudios peruanoss."))) OR ("tres estudios urbano."))*.
• Removing quotes may allow a broader search: (((( series estudios peruanoss. ) or ( seis estudios peruanoss. ))) or ( tres estudios urbano. ))*.