Mercy Otis Warren (1805). “History of the Rise, Progress, and Termination of the American Revolution: Interspersed with Biographical, Political and Moral Observations”, p.5
Maria Montessori, Gerald Lee Gutek (2004). “The Montessori Method: The Origins of an Educational Innovation : Including an Abridged and Annotated Edition of Maria Montessori's The Montessori Method”, p.114, Rowman & Littlefield