Perhaps you should try some spelling variations:
"series estudios ensayos." » "series estudios etnicos.", "serie estudios ensayos.", "seis estudios ensayos.", "tres estudios ensayos."
"tres estudioss urbano." » "tres estudios urbanos.", "tres estudio urbano.", "tres estudios urbano.", "tres estadios urbano.", "otros estudios urbano."
"series estudios urbano." » "serie estudios urbano.", "seis estudios urbano.", "tres estudios urbano.", "series estudios urbanos.", "series estudio urbano.", "series estudios peruanos."

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

• Performing a fuzzy search may retrieve terms with similar spellings: (("tres estudioss urbano.") or ((("series estudios urbano.") or ("series estudios ensayos."))))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (("tres estudioss urbano.") OR ((("series estudios urbano.") OR ("series estudios ensayos."))))*.
• Removing quotes may allow a broader search: (( tres estudioss urbano. ) or ((( series estudios urbano. ) or ( series estudios ensayos. ))))*.