1. Ph. Forchheimer 1914 70ff
2. G. Stokes On the e'fect of the internal friction of fluids on the motion of penduiums Camb. Teans. 1851
3. L. Prandtl Verhandl des III. intern, Math Kongres 1904 (Heldelberg) 1905 484
4. Disseration Göttingen 1907;Blasiusi;Zeitschr, für Math n Pbys,1908
5. E. Boltze 1908