backstab vs get at

backstab

verb
  • to attack someone (especially verbally) unfairly in a deceitful, underhand, or treacherous manner, especially when they're not present in the place or situation that it happens. (as if stabbing them in the back). See backbite. 

get at

verb
  • To attack verbally or physically; to annoy, bother. 

  • To manage to gain access to. 

  • To understand or ascertain by investigation. 

  • To persuade by intimidation, to tamper with. 

  • To begin working on or dealing with. 

  • To contact someone. 

  • To mean, signify. 

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