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."

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. ))*.