Robert Brain and M. Norton Wise, «Muscles and Engines: Indicator Diagrams and Helmholtz's Graphical Methods,» in Universalgenie Helmholtz: Rückblick nach 100 Jahren, ed. Lorenz Krüger (Berlin: Akademie-Verlag, 1994), 124–145; Lorraine Daston and Peter Galison, «The Image of Objectivity,» Representations 40 (1992): 81–128.
