1. L. Da Vinci, The Notebooks of Leonardo da Vinci English translation: http://italian.classic-literature.co.uk/leonardo-da-vinci/ ; also http://www.gutenberg.org/etext/5000 . R.A. Granger, Fluid Mechanics (Dover, Mineola, New York, 1995), p. 441
2. L. Prandtl, in Verhandlungen III Internationaler Mathematiker Kongress Heidelberg, 1904 (Teubner, Heidelberg, 1905), p. 484; Eng. trans. NACA, 452 (1928)
3. J.D. Anderson, Jr., Phys. Today 58, (2005)
4. E.C. Maskell, Roy. Aircraft Est. Rep. No. AERO.2565 (1955)
5. D.N. Kenwright, C. Henze, C. Levit, IEEE Trans. Visual. Comp. Graph. 5, 135 (1999)