Perhaps you should try some spelling variations:
"series estudios hispanos." » "series estudios hispano.", "series estudios hispanicos.", "series estudios espanoles.", "serie estudios hispanos.", "seis estudios hispanos.", "leyes estudios hispanos."
"tres estudios etnicos." » "tres estudios criticos.", "tres estudios biblicos.", "otros estudios etnicos.", "dos estudios etnicos.", "dios estudios etnicos."
"los estudios etnicos." » "los estudios criticos.", "los estudios biblicos."

Try widening your search to All Fields.

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: (((("tres estudios etnicos.") or ("los estudios etnicos."))) or ("series estudios hispanos."))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (((("tres estudios etnicos.") OR ("los estudios etnicos."))) OR ("series estudios hispanos.")).
• Removing quotes may allow a broader search: (((( tres estudios etnicos. ) or ( los estudios etnicos. ))) or ( series estudios hispanos. )).
• Adding a wildcard symbol may retrieve word variants: (((("tres estudios etnicos.") or ("los estudios etnicos."))) or ("series estudios hispanos."))*.