Perhaps you should try some spelling variations:
"tres estudios biblicos." » "tres estudios criticos.", "tres estudios filologicos.", "otros estudios biblicos.", "los estudios biblicos.", "dos estudios biblicos."
"tres estudios etnicos." » "tres estudios criticos.", "otros estudios etnicos.", "los estudios etnicos.", "dos estudios etnicos."
"serie estudos hispanos." » "serie estudios hispano.", "serie estudios hispanicos.", "serie estilo hispano.", "serie estudios hispanos.", "series estudios hispanos.", "serie estado 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 etnicos.") OR ("tres estudios biblicos."))) or ("serie estudos hispanos."))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (((("tres estudios etnicos.") OR ("tres estudios biblicos."))) OR ("serie estudos hispanos.")).
• The words AND, OR and NOT may confuse the search; try adding quotes: "((((\"tres estudios etnicos.\") OR (\"tres estudios biblicos.\"))) or (\"serie estudos hispanos.\"))".
• Removing quotes may allow a broader search: (((( tres estudios etnicos. ) OR ( tres estudios biblicos. ))) or ( serie estudos hispanos. )).
• Adding a wildcard symbol may retrieve word variants: (((("tres estudios etnicos.") OR ("tres estudios biblicos."))) or ("serie estudos hispanos."))*.