documentation vs mailshots

documentation

noun
  • Documents that explain the operation of a particular machine or software program. 

  • Documentary evidence and sources. 

  • Something transposed from a thought to a document; the written account of an idea. 

  • Comments that explain the usage of individual functions, libraries and blocks of code. 

  • A documentary. 

mailshots

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