piece of paper vs stipulation

piece of paper

noun
  • A marriage certificate. 

  • A single sheet or scrap of paper. 

stipulation

noun
  • The act of stipulating; a contracting or bargaining; an agreement. 

  • Something that is stated or stipulated as a condition of an agreement. 

  • The situation, arrangement, and structure of the stipules. 

  • A goal to be achieved in a chess problem; for example, to checkmate Black within a specified number of moves. 

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