Perhaps you should try some spelling variations:
"dios estudios peruanos." » "dios estudios americanos.", "dios estudios ensayos.", "dios estudios cervantinos.", "dos estudios peruanos.", "los estudios peruanos.", "otros estudios peruanos."
"series estudios urbano." » "serie estudios urbano.", "seis estudios urbano.", "tres estudios urbano.", "series estudio urbano.", "series estudios hispano.", "series d'estudis urbans."
"series estudios urbanos." » "serie estudios urbanos.", "seis estudios urbanos.", "tres estudios urbanos.", "series estudio urbanos.", "series estudios hispanos.", "series d'estudis urbanss."

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