paper trail vs verification

paper trail

noun
  • A written record, history, or collection of evidence. 

  • Records left by a person or organization in the course of activities. 

  • Physical evidence of something that occurred in the past. 

verification

noun
  • The act of verifying. 

  • The state of being verified. 

  • Confirmation; authentication. 

  • A formal phrase used in concluding a plea, to denote confirmation by evidence. 

  • The operation of testing the equation of a problem, to see whether it truly expresses the conditions of the problem. 

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