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