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