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

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 estudio urbano.") OR ("series estudios urbanos."))) or ("los estudios peruanos."))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (((("series estudio urbano.") OR ("series estudios urbanos."))) OR ("los estudios peruanos.")).
• The words AND, OR and NOT may confuse the search; try adding quotes: "((((\"series estudio urbano.\") OR (\"series estudios urbanos.\"))) or (\"los estudios peruanos.\"))".
• Removing quotes may allow a broader search: (((( series estudio urbano. ) OR ( series estudios urbanos. ))) or ( los estudios peruanos. )).
• Adding a wildcard symbol may retrieve word variants: (((("series estudio urbano.") OR ("series estudios urbanos."))) or ("los estudios peruanos."))*.