code: def get_references(chebi_ids):
      '''Returns references'''
      references = []
      chebi_ids = [str(chebi_id) for chebi_id in chebi_ids]
  
      filename = get_file('reference.tsv.gz')
  
      with io.open(filename, 'r', encoding='cp1252') as textfile:
          next(textfile)
  
          for line in textfile:
              tokens = line.strip().split('\t')
  
              if tokens[0] in chebi_ids:
                  # Append Reference:
                  if len(tokens) > 3:
                      ref = Reference(tokens[1], tokens[2], tokens[3],
                                      tokens[4])
                  else:
                      ref = Reference(tokens[1], tokens[2])
  
                  references.append(ref)
      return referencef get_references(chebi_ids):
      '''Returns references'''
      references = []
      chebi_ids = [str(chebi_id) for chebi_id in chebi_ids]
  
      filename = get_file('reference.tsv.gz')
  
      with io.open(filename, 'r', encoding='cp1252') as textfile:
          next(textfile)
  
          for line in textfile:
              tokens = line.strip().split('\t')
  
              if tokens[0] in chebi_ids:
                  # Append Reference:
                  if len(tokens) > 3:
                      ref = Reference(tokens[1], tokens[2], tokens[3],
                                      tokens[4])
                  else:
                      ref = Reference(tokens[1], tokens[2])
  
                  references.append(ref)
      return references
docs: Returns references