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.", "serie estudios hispanos.", "seis estudios hispanos.", "sociales estudios hispanos."
"leyes estudios hispanos." » "leyes estudios hispano.", "leyes estudios hispanicos.", "leyes estudios espanoles.", "los estudios hispanos.", "seis estudios hispanos."

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