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