get at vs undertake

get at

verb
  • To begin working on or dealing with. 

  • To manage to gain access to. 

  • To understand or ascertain by investigation. 

  • To persuade by intimidation, to tamper with. 

  • To contact someone. 

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

  • To mean, signify. 

undertake

verb
  • To take upon oneself; to start, to embark on (a specific task etc.). 

  • To commit oneself (to an obligation, activity etc.). 

  • To pass a slower moving vehicle on the curbside rather than on the side closest to oncoming traffic. 

noun
  • The passing of slower traffic on the curbside rather than on the side closest to oncoming traffic. 

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