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