[19]. Imbert, Etudes experimentales de travail professionnel ouvrier, Sur la fatigue engendree par les mouvements rapides.
[20]. William James, Psychology, Briefer Course, p. 134.
[21]. Ibid., p. 138. William James, Psychology, Advanced Course. p. 112.
[22]. F.B. Gilbreth, Bricklaying System, p. 142.
[23]. Stratton, Experimental Psychology and Culture, p. 214.
[24]. Prof. Bain, quoted In William James' Psychology, Briefer Course, pp. 145-147.
[25]. F.B. Gilbreth, Bricklaying System, para. 18-19.
[26]. M.W. Calkins, A First Book in Psychology, p. 354.
[27]. James Sully, The Teacher's Handbook of Psychology, p. 119.
[28]. Stratton, Experimental Psychology and Culture, p. 99.