employ vs specialization

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. 

specialization

noun
  • The act or process of specializing. 

  • The area in which someone specializes. 

  • The adaptation of an organism to a specific environment, or adaptation of an organ to a particular function. 

  • A proof, axiom, problem, or definition whose cases are completely covered by another, broader concept. 

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