chivvy vs keep on at

chivvy

verb
  • To coerce or hurry along, as by persistent request. 

  • To subject to harassment or verbal abuse. 

  • To sneak up on or rapidly approach. 

  • To pursue as in a hunt. 

noun
  • Something that encourages one to act; a goad, a spur. 

keep on at

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