Skinner, B. F. (1953). The Analysis of Behavior. Science and human behavior. Science and human Behavior. (pp.72-80) Oxford, England: The Macmillan Company. Recuperado de: https://books.google.com.mx/books?id=Pjjknd1HREIC&printsec=frontcover&hl=es#v=onepage&q&f=false.