function rtf()
    {
        $ret = "{\\rtf\n";
        foreach ($this->data as $entry) {
            $line = $this->rtfstring;
            $title = '';
            $journal = '';
            $year = '';
            $authors = '';
            if (array_key_exists('title', $entry)) {
                $title = $this->_unwrap($entry['title']);
            }
            if (array_key_exists('journal', $entry)) {
                $journal = $this->_unwrap($entry['journal']);
            }
            if (array_key_exists('year', $entry)) {
                $year = $this->_unwrap($entry['year']);
            }
            if (array_key_exists('author', $entry)) {
                if ($this->_options['extractAuthors']) {
                    $tmparray = array(); //In this array the authors are saved and the joind with an and
                    foreach ($entry['author'] as $authorentry) {
                        $tmparray[] = $this->_formatAuthor($authorentry);
                    }
                    $authors = join(', ', $tmparray);
                } else {
                    $authors = $entry['author'];
                }
            }
            if (('' != $title) || ('' != $journal) || ('' != $year) || ('' != $authors)) {
                $line = str_replace("TITLE", $title, $line);
                $line = str_replace("JOURNAL", $journal, $line);
                $line = str_replace("YEAR", $year, $line);
                $line = str_replace("AUTHORS", $authors, $line);
                $line .= "\n\\par\n";
                $ret .= $line;
            } else {
                $this->_generateWarning('WARNING_LINE_WAS_NOT_CONVERTED', '', print_r($entry, 1));
            }
        }
        $ret .= '}';
        return $ret;
    }