Perhaps you should try some spelling variations:
"serie lectura de clases." » "serie lecturas de clases.", "semir lectura de clases.", "serra lectura de clases.", "serie lectura de clase."
"serie lectura de bases." » "serie lecturas de bases.", "semir lectura de bases.", "serra lectura de bases.", "serie lectura de base."
"serie letras la clase." » "serie las la clase.", "serie tras la clase.", "serie letras de clase.", "serie letras y clase."

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

• Performing a fuzzy search may retrieve terms with similar spellings: (("serie letras la clase.") or ((("serie lectura de clases.") OR ("serie lectura de bases."))))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (("serie letras la clase.") OR ((("serie lectura de clases.") OR ("serie lectura de bases.")))).
• The words AND, OR and NOT may confuse the search; try adding quotes: "((\"serie letras la clase.\") or (((\"serie lectura de clases.\") OR (\"serie lectura de bases.\"))))".
• Removing quotes may allow a broader search: (( serie letras la clase. ) or ((( serie lectura de clases. ) OR ( serie lectura de bases. )))).
• Adding a wildcard symbol may retrieve word variants: (("serie letras la clase.") or ((("serie lectura de clases.") OR ("serie lectura de bases."))))*.