public function setDate($date)
    {
        if (!is_numeric($date))
        {
            $date = strtotime($date);
        }

        if ($this->version == Eresus_Feed_Writer::ATOM)
        {
            $tag = 'updated';
            $value = date(DATE_ATOM, $date);
        }
        elseif ($this->version == Eresus_Feed_Writer::RSS2)
        {
            $tag = 'pubDate';
            $value = date(DATE_RSS, $date);
        }
        else
        {
            $tag = 'dc:date';
            $value = date("Y-m-d", $date);
        }

        $this->addElement($tag, $value);
    }