1. W. D. Hayes,Gasdynamic Discontinuities(Princeton University Press, Princeton, New Jersey, 1960);
2. M. J. Light-hill, inSurveys in Mechanics, edited by G. K. Batchelor and R. M. Davies (Cambridge University Press, New York, 1956).
3. F. S. Sherman and L. Talbot, inRarefied Gas Dynamics, edited by F. M. Devienne (Pergamon Press, New York, 1960).
4. H. W. Liepmainn and A. Roshko,Elments of Gag-dynamics(John Wiley & Sons, Inc., New York 1957), p. 57.