code: def get_document_summary(self, N=None, cite_sort=True, refresh=True):
          
          abstracts = self.get_abstracts(refresh=refresh)
  
          if cite_sort:
              counts = [(a, int(a.citedby_count)) for a in abstracts]
              counts.sort(reverse=True, key=itemgetter(1))
              abstracts = [a[0] for a in counts]
  
          if N is None:
              N = len(abstracts)
  
          s = [u'{0} of {1} documents'.format(N, len(abstracts))]
  
          for i in range(N):
              s += ['{0:2d}. {1}\n'.format(i + 1, str(abstracts[i]))]
  
          return '\n'.join(s)
docs: Return a summary string of documents.
  
          Parameters
          ----------
          N : int or None (optional, default=None)
              Maximum number of documents to include in the summary.
              If None, return all documents.
  
          cite_sort : bool (optional, default=True)
              Whether to sort xml by number of citations, in decreasing order,
              or not.
  
          refresh : bool (optional, default=True)
              Whether to refresh the cached abstract file (if it exists) or not.
  
          Returns
          -------
          s : str
              Text summarizing an author's documents.