Hermano Frid Helge Holden Kenneth H. Karlsen L<sup>∞</sup> Solutions for a Model of Nonisothermal Polytropic Gas Flow. 2253-2274 2011 43 SIAM J. Math. Analysis 5 http://dx.doi.org/10.1137/110824218 db/journals/siamma/siamma43.html#FridHK11