def authors_et_al(self, max_authors=5):
        """
        Return string with a truncated author list followed by 'et al.'
        """
        author_list = self._author_list
        if len(author_list) <= max_authors:
            authors_et_al = self.authors
        else:
            authors_et_al = ", ".join(
                self._author_list[:max_authors]) + ", et al."
        return authors_et_al
Return string with a truncated author list followed by 'et al.'