1. This information about events before the 1880s is taken from Eugen Diesel, Gustav Goldbeck and Friedrich Schildberger, From Engines to Autos. Five Pioneers in Engine Development and their Contribution to the Automotive Industry (Chicago, 1960). The book was published first in Stuttgart in German in 1957.
2. For reproduction of both patents see H. Ch. Seherr-Thoss, Zwei Männer – ein Stern (Düsseldorf, 1984), vol. I, pp. 18, 25 ff.
3. F. Sass, Geschichte des deutschen Verbrennungsmotorenbaues (Berlin, 1962) p. 86.
4. A. Bird, The Motor Car, 1765–1914 (London, 1960), p. 27.
5. J. M. Laux, In First Gear: The French Automobile Industry to 1914 (Liverpool, 1976) p. 20.