paperback vs playbook

paperback

noun
  • A book with flexible binding. 

adj
  • Having flexible binding. 

verb
  • To issue or publish (a book) in a paperback edition. 

playbook

noun
  • A book containing the text of a play or plays. 

  • A set of commonly employed tactics and strategies. 

  • A book of games and amusements for children. 

  • A book of strategies (plays) for use in American football (and by extension other sports or disciplines). 

How often have the words paperback and playbook occurred in a corpus of books? (source: Google Ngram Viewer )