lithograph vs mezzotint

lithograph

noun
  • A printed image produced by lithography. 

verb
  • To create a copy of an image through lithography. 

mezzotint

noun
  • A form of intaglio etching in which a metal plate is roughened evenly and then smoothed to bring out an image. 

  • An etching or print made using this method. 

verb
  • To make such etchings 

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