Perhaps you should try some spelling variations:
"competencias mathematics computer programming." » "competencias matematicas computer programming.", "competencias matematica computer programming.", "competencia matematica computer programming.", "competencias mathematics computer programs.", "competencias mathematics computer program."
"basicas matematicas como programar." » "comicas matematicas como programar.", "benditas matematicas como programar.", "fisica matematica como programar.", "basicas matematica como programar.", "basicas matematicas con programar.", "basicas matematica tomo programar.", "basicas matematicas como programa.", "basicas matematicas campo programa.", "basicas matematicas con programa."

Try widening your search to All Fields.

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• Performing a fuzzy search may retrieve terms with similar spellings: (("basicas matematicas como programar.") or ("competencias mathematics computer programming."))~.
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• Adding a wildcard symbol may retrieve word variants: (("basicas matematicas como programar.") or ("competencias mathematics computer programming."))*.