Perhaps you should try some spelling variations:
"serie cartas de bases." » "serie actas de bases.", "serie notas de bases.", "serie art de bases.", "serie carta de bases."
"serie atlas de clase." » "serie las de clase.", "serie aula de clase.", "serie actas de clase.", "serie atlas de clacso.", "serie atlas la clase."
"serie arte de clases." » "serie arte de clacsos.", "serie arte la clases."

You may be able to get more results by adjusting your search query.

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