def affiliation_history(self):
        """List of ScopusAffiliation objects representing former
        affiliations of the author.  Only affiliations with more than one
        publication are considered.
        """
        aff_ids = [e.attrib.get('affiliation-id') for e in
                   self.xml.findall('author-profile/affiliation-history/affiliation')
                   if e is not None and len(list(e.find("ip-doc").iter())) > 1]
        return [ScopusAffiliation(aff_id) for aff_id in aff_ids]
List of ScopusAffiliation objects representing former
        affiliations of the author.  Only affiliations with more than one
        publication are considered.