docs: def get_author(self, **kwargs):
          """Determine the authors from the creator field."""
          qualifier = kwargs.get('qualifier', '')
          children = kwargs.get('children', [])
          creator_type_per = False
          author_name = None
          # Find the creator type in children.
          for child in children:
              if child.tag == 'type' and child.content == 'per':
                  creator_type_per = True
              # Get the author name.
              elif child.tag == 'name':
                  author_name = child.content
          if qualifier == 'aut' and creator_type_per and author_name:
              return author_name
  
          return None