call up vs hark back

call up

verb
  • To call on the telephone. 

  • To select e.g. to a sports squad. 

  • To summon (someone) to report for military service. 

  • To retrieve from personal or computer memory. 

noun
  • An order to report for military service. 

hark back

verb
  • To call back (hounds); to recall. 

  • To allude, return, or revert (to a subject previously mentioned, etc.); also, to evoke, or long or pine for (a past era or event). 

  • To return to where one has previously been; to retrace one's steps. 

  • Of hounds: to retrace a course in order to pick up the lost scent of prey. 

noun
  • An act of hounds retracing a course in order to pick up the lost scent of prey. 

  • An act of alluding, returning, or reverting (to a subject previously mentioned, etc.); also, an act of evoking, or longing or pining for (a past era or event). 

How often have the words call up and hark back occurred in a corpus of books? (source: Google Ngram Viewer )