Perhaps you should try some spelling variations:
"serie cartas de bases." » "serie arte de bases.", "serie notas de bases.", "serie art de bases.", "serie artes de bases.", "serie arts de bases."
"serie actas de clases." » "serie letras de clases.", "serie fichas de clases.", "serie actas de clase.", "serie actas del clases."
"serie carta de clases." » "serie arte de clases.", "serie art de clases.", "serie carta de clase."

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 actas de clases.") or ((("serie cartas de bases.") or ("serie carta de clases."))))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (("serie actas de clases.") OR ((("serie cartas de bases.") OR ("serie carta de clases.")))).
• Removing quotes may allow a broader search: (( serie actas de clases. ) or ((( serie cartas de bases. ) or ( serie carta de clases. )))).
• Adding a wildcard symbol may retrieve word variants: (("serie actas de clases.") or ((("serie cartas de bases.") or ("serie carta de clases."))))*.