1. Hyperbolic systems of conservation laws II
2. K. O. Friedrichs, Communs. Pure and Appl. Math. 1, (1948).
3. K. O. Friedrichs, “Nichtlineare Differentialgleichungen; (Stoss-und Expansionswellen),” Gottingen, 1955.
4. R. Courant and K. O. Friedrichs,Supersonic Flow and Shock Waves(Interscience Publishers, Inc., New York, 1948).
5. Resolution of an Initial Shear-Flow Discontinuity in One-Dimensional Hydromagnetic Flow.