Perhaps you should try some spelling variations:
"series estudios peruanos." » "series estudios americanos.", "series estudios ensayos.", "series estudios cervantinos.", "serie estudios peruanos.", "seis estudios peruanos.", "leyes estudios peruanos."
"series estudios urbanos." » "serie estudios urbanos.", "seis estudios urbanos.", "leyes estudios urbanos."
"tres estudios urbanos." » "otros estudios urbanos.", "los estudios urbanos.", "dos estudios urbanos."

Try widening your search to All Fields.

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