Perhaps you should try some spelling variations:
"serie obligaciones internacionales." » "serie relaciones internacionales.", "serie migraciones internacionales.", "serie operaciones internacionales.", "serie publicaciones internacionales.", "de obligaciones internacionales.", "civil obligaciones internacionales."
"series publications internacional." » "series publicacion internacional.", "series publica internacional.", "series publico internacional.", "serie publicaciones internacional.", "sefardies publicaciones internacional.", "student publications internacional."

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: (("serie obligaciones internacionales.") or ("series publications internacional."))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (("serie obligaciones internacionales.") OR ("series publications internacional.")).
• Removing quotes may allow a broader search: (( serie obligaciones internacionales. ) or ( series publications internacional. )).
• Adding a wildcard symbol may retrieve word variants: (("serie obligaciones internacionales.") or ("series publications internacional."))*.