Perhaps you should try some spelling variations:
"serie notas a clave." » "serie actas a clave.", "serie notas en clave.", "serie notas i clave.", "serie notas y clave.", "serie notas una clave."
"serie notas la clave." » "serie actas la clave.", "serie poetas la clave.", "serie notas mas clave.", "serie notas en clave.", "serie notas la clase.", "serie notas la llave.", "serie notas li clave.", "serie notas ly clave.", "serie notas luna clave."
"serie notas de clave." » "serie actas de clave.", "serie notas de claves.", "serie notas de clase.", "serie notas de clases."

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