autograph vs initials

autograph

noun
  • A person’s own handwriting, especially the signature of a famous or admired person. 

  • A person's signature used as a mark of formal approval. 

  • A manuscript in the author’s handwriting. 

verb
  • To write something in one's own handwriting 

  • To sign, or write one’s name or signature on a book etc 

adj
  • Made by the artist himself or herself; authentic. 

  • Written in the author’s own handwriting. 

initials

noun
  • An abbreviation of a person's name, constructed by taking the initial letters of first, last, and sometimes middle name(s). See monogram 

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