correspond vs work through

correspond

verb
  • To be equivalent or similar in character, quantity, quality, origin, structure, function etc. 

  • to exchange messages, especially by postal letter, over a period of time. 

work through

verb
  • Used other than figuratively or idiomatically: see work, through. 

  • To get past a difficult or stressful situation by thinking or talking about it. 

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