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