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

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

• If you are trying to use Boolean operators, they must be ALL CAPS: (((("series estudioss peruanoss.") OR ("serie estudios peruanos."))) OR ("dos estudios urbanos."))~.
• Removing quotes may allow a broader search: (((( series estudioss peruanoss. ) or ( serie estudios peruanos. ))) or ( dos estudios urbanos. ))~.
• Adding a wildcard symbol may retrieve word variants: (((("series estudioss peruanoss.") or ("serie estudios peruanos."))) or ("dos estudios urbanos."))*.