indenture vs piece of paper

indenture

noun
  • A document, written as duplicates separated by indentations, specifying such a contract. 

  • A contract which binds a person to work for another, under specified conditions, for a specified time (often as an apprentice). 

  • An indentation; a recess. 

verb
  • To indent; to make hollows, notches, or wrinkles in; to furrow. 

  • To bind a person under such a contract. 

piece of paper

noun
  • A single sheet or scrap of paper. 

  • A marriage certificate. 

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