1. L. Prandtl , in Verhandlungen des dritten internationalen Mathematiker-Kongresses in Heidelberg 1904,
A. Krazer , ed. Teubner, Leipzig, Germany (1905), p. 484.
2. English trans. in Early Developments of Modern Aerodynamics,
J. A. K. Ackroyd ,
B. P. Axcell ,
A. I. Ruban , eds. Butterworth-Heinemann, Oxford, UK (2001), p. 77.
3. Fluid Mechanics in the First Half of this Century