Perhaps you should try some spelling variations:
"tres estudios peruanoss." » "tres estudios peruanos.", "otros estudios peruanoss.", "los estudios peruanoss.", "dos estudios peruanoss."
"series estudios urbano." » "serie estudios urbano.", "seis estudios urbano.", "leyes estudios urbano.", "series estudio urbano.", "series estudios peruanos.", "series estudios hispano."
"tres estudios urbanos." » "tres estudio urbanos.", "tres estudios peruanoss.", "tres estudios hispanos.", "otros estudios urbanos.", "los estudios urbanos.", "dos estudios urbanos."

You may be able to get more results by adjusting your search query.

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