assent vs authorization

assent

noun
  • agreement; act of agreeing 

verb
  • To agree to a proposal. 

authorization

noun
  • An act of authorizing. 

  • (A document giving) formal sanction, permission or warrant. 

  • Permission. 

  • Permission, possibly limited, to spend funds for a specific budgetary purpose. 

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