carbon copy vs microfiche

carbon copy

noun
  • A copy produced in an alternated stack of ordinary sheets of paper and carbon papers. The pressure applied on the top sheet (by a pen or typewriter) causes every carbon paper to release its carbon cover, thus reproducing the writing on the subjacent layers of paper. 

  • A duplicate copy of an email. 

  • Any duplicate. 

verb
  • To send a duplicate copy of an email to. 

  • To create a carbon copy of. 

microfiche

noun
  • A sheet of microfilm, six by four inches, holding several hundred reduced images of document pages, read using a microfiche reader or microfilm reader. 

  • A device used to magnify and read these sheets. 

verb
  • To convert (documents) to microfiche format. 

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