walkout vs work-to-rule

walkout

noun
  • A similar mass action of people leaving a place as a form of protest. 

  • A sudden stoppage of work. 

  • A part of the squat exercise wherein one has to step out from the rack (“walk out” the weight) in order not to hit it during execution. 

work-to-rule

noun
  • A labor protest in which employees do only the minimum work required by the rules of a workplace, following safety or other regulations to the letter in order to cause a slowdown. 

adj
  • Of or pertaining to such a protest. 

How often have the words walkout and work-to-rule occurred in a corpus of books? (source: Google Ngram Viewer )