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