author vs formulate

author

verb
  • To create a work as its author. 

noun
  • Someone who writes books for a living. 

  • The originator or creator of a work, especially of a literary composition. 

formulate

verb
  • To put into a clear and definite form of statement or expression. 

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