Perhaps you should try some spelling variations:
"dios estudios peruanos." » "dios estudios urbanos.", "dios estudios americanos.", "dios estudios ensayos.", "dos estudios peruanos.", "los estudios peruanos.", "otros estudios peruanos."
"series estudios urbano." » "serie estudios urbano.", "seis estudios urbano.", "leyes estudios urbano.", "series estudios urbanos.", "series estudio urbano.", "series estudios hispano."
"tres estudios urbano." » "tres estudios urbanos.", "tres estudio urbano.", "tres estudios hispano.", "otros estudios urbano.", "los estudios urbano.", "dos estudios 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 estudios urbano.") OR ("tres estudios urbano."))) or ("dios estudios peruanos."))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (((("series estudios urbano.") OR ("tres estudios urbano."))) OR ("dios estudios peruanos."))*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((((\"series estudios urbano.\") OR (\"tres estudios urbano.\"))) or (\"dios estudios peruanos.\"))*".
• Removing quotes may allow a broader search: (((( series estudios urbano. ) OR ( tres estudios urbano. ))) or ( dios estudios peruanos. ))*.