public function urlTo($cql, $start = 1, $count = 10, $extraParams = array())
    {
        $qs = array(
            'operation' => 'searchRetrieve',
            'version' => $this->version,
            'recordSchema' => $this->schema,
            'maximumRecords' => $count,
            'query' => $cql
        );

        if ($start != 1) {
            // At least the BIBSYS SRU service, specifying startRecord results in
            // a less clear error message when there's no results
            $qs['startRecord'] = $start;
        }

        foreach ($extraParams as $key => $value) {
            $qs[$key] = $value;
        }

        return $this->url . '?' . http_build_query($qs);
    }