employ vs supervision

employ

noun
  • The state of being an employee; employment. 

verb
  • To hire (somebody for work or a job). 

  • To use (somebody for a job, or something for a task). 

  • To make busy. 

supervision

noun
  • The act or instance of supervising. 

  • A tutorial session for an individual student or a small group. 

  • Responsible oversight. 

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