Perhaps you should try some spelling variations:
"seis estudios peruanoss." » "seis estudios peruanos.", "los estudios peruanoss.", "dios estudios peruanoss.", "pons estudios peruanoss."
"tres estudios hispano." » "otros estudios hispano.", "los estudios hispano.", "dios estudios hispano.", "tres estudios hispana.", "tres estudios hispanic."
"dos estudios urbanos." » "los estudios urbanos."

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 ("dos estudios urbanos."))) or ("tres estudios hispano."))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (((("seis estudios peruanoss.") OR ("dos estudios urbanos."))) OR ("tres estudios hispano."))*.
• Removing quotes may allow a broader search: (((( seis estudios peruanoss. ) or ( dos estudios urbanos. ))) or ( tres estudios hispano. ))*.