laissez-passer vs travel document

laissez-passer

noun
  • A pass or permit; a document permitting the bearer to travel, sometimes issued as an emergency passport. 

travel document

noun
  • An identity document similar to a passport, but which does not confer proof of citizenship from the issuing country. 

  • An identity document issued by a government or international treaty organization to facilitate the movement of individuals or small groups of persons across international boundaries, such as a passport. 

How often have the words laissez-passer and travel document occurred in a corpus of books? (source: Google Ngram Viewer )