Perhaps you should try some spelling variations:
"serie estudios ensayos." » "serie estudios etnicos."
"serie estudios urbano." » "serie estudios urbanos.", "serie estudio urbano.", "serie estudios peruanos."
"series estudios urbano." » "series estudios urbanos.", "series estudio urbano.", "series estudios peruanos.", "seis estudios urbano.", "tres estudios urbano.", "leyes 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: (((("serie estudios urbano.") or ("serie estudios ensayos."))) or ("series estudios urbano."))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (((("serie estudios urbano.") OR ("serie estudios ensayos."))) OR ("series estudios urbano."))*.
• Removing quotes may allow a broader search: (((( serie estudios urbano. ) or ( serie estudios ensayos. ))) or ( series estudios urbano. ))*.