?url_ver=Z39.88-2004&rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&rft.aufirst=Richard&rft.au=Cowan%2C+Richard&rft.aulast=Cowan&rft.pages=180-188&rft.title=Anales+de+Psicologia&rft.volume=24&rft.atitle=Why+children+differ+in+their+mathematical+attainment+at+primary+school&rft.issue=2&rft.issn=0212-9728&rft.date=December+2008&rft.genre=article