get back to vs request

get back to

verb
  • To return contact with (someone); to return to someone in response to a request 

  • Return to (an activity) 

request

verb
  • To ask (somebody) to do something. 

  • To ask for (something). 

noun
  • A message sent over a network to a server. 

  • Act of requesting (with the adposition at in the presence of possessives, and on in their absence). 

  • Condition of being sought after. 

  • A formal message requesting something. 

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