1. Courant, R., & K. Friedrichs: Supersonic Flow and Shock Waves. New York: Interscience 1948.
2. Courant, R., & D. Hilbert: Methoden der Mathematischen Physik, Bd. 2. Berlin: Springer 1936.
3. Dolidze, D. E.: Doklady Akademii Nauk SSSR. 96, 437–439 (1954).
4. Foá, E.: Sull'impiego dell'analisi dimensionale nello studio del moto turbolento. L'industria (Milano) 43, 426–429 (1929).
5. Friedrichs, K.: Symmetric hyperbolic linear differential equations. Communications on Pure and Applied Math. 7, 345–392 (1954).