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