A. Pimloche, Pestalozzi and the Foundation of the Modern Elementary School, p. 139.

Friedrich Froebel, Education of Man, "To secure for this ability skill and directness, to lift it into full consciousness, to give it insight and clearness, and to exalt it into a life of creative freedom, is the business of the subsequent life of man in successive stages of development and cultivation."

W.P. Gillette, Cost Analysis Engineering, p. 3.

F.W. Taylor, Paper 647, A.S.M.E., para. 33, para. 59.

Hugo Diemer, Factory Organization and Administration, p. 5.

James M. Dodge, Paper 1115, A.S.M.E., p. 723.

F.W. Taylor, Shop Management, para. 310-311, Harper Ed., pp. 142-143.