F.W. Taylor, Principles of Scientific Management, p. 137. (Harper & Bros.)

William James, Psychology, Briefer Course, p. 1.

Hugo Münsterberg, American Problems, p. 34.

Mary Whiton Calkins, A First Book in Psychology, p. 1.

James Sully, Teacher's Handbook of Psychology, p. 14.

James Sully, Teacher's Handbook of Psychology, p. 577.

H.L. Gantt, Work, Wages and Profits, p. 52.

F.W. Taylor, Shop Management, p. 25. (Harper & Bros.)

F.B. Gilbreth, Motion Study, p. 7.

L.B. Blan, A Special Study of the Incidence of Retardation, p. 89.

Hugo Münsterberg, American Problems, pp. 38-39.

F.B. Gilbreth, Cost Reducing System, Chap. III.

Mary Whiton Calkins, A First Book in Psychology, p. 273.

Sully, The Teacher's Handbook of Psychology, p. 1.

Ibid., p. 54.