def to_xml(self):
     doc = BioDesDoc()
     bioport_id = self.get_biographies()[0].get_bioport_id()
     # add the basic onfirmation
     doc.from_args(
         naam_publisher='Het Biografisch Portaal',
         url_biografie='http://www.biografischportaal.nl/persoon/%s' % bioport_id,
         url_publisher='http://www.biografischportaal.nl',
         namen=self.get_names(),
         bioport_id=bioport_id,
         sex=self.get_value('sex'),
     )
     # add the events
     for event_type in ['birth', 'death', 'funeral', 'baptism', 'floruit']:
         event = self.get_event(event_type)
         if event is not None:
             doc._add_event_element(event)
     # add illustrations
     for ill in self.get_illustrations():
         doc._add_figure(url=ill.source_url, head=ill.caption)
     # add links to all sources
     for bio in self.get_biographies():
         if bio.get_source().id != 'bioport':
             # construct a bibl element
             bibl = SubElement(doc.get_element_biography(), 'bibl')
             publisher = SubElement(bibl, 'publisher')
             publisher.text = bio.get_value('name_publisher')
             ref = SubElement(bibl, 'ref')
             ref.attrib['target'] = bio.get_value('url_biography')
             author = bio.get_value('author')
             if author:
                 for s in author:
                     el_author = SubElement(bibl, 'author')
                     el_author.text = s
     return doc