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

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 criticos.") or ((("series estudios hispanos.") OR ("serie estudios hispanos."))))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (("tres estudios criticos.") OR ((("series estudios hispanos.") OR ("serie estudios hispanos.")))).
• The words AND, OR and NOT may confuse the search; try adding quotes: "((\"tres estudios criticos.\") or (((\"series estudios hispanos.\") OR (\"serie estudios hispanos.\"))))".
• Removing quotes may allow a broader search: (( tres estudios criticos. ) or ((( series estudios hispanos. ) OR ( serie estudios hispanos. )))).
• Adding a wildcard symbol may retrieve word variants: (("tres estudios criticos.") or ((("series estudios hispanos.") OR ("serie estudios hispanos."))))*.