1. O. A. Oleinik, A. S. Kalashnikov, and Yui-Lin' Chzhou, ?The Cauchy problem and boundary-value problems for equations of the nonstationary filtration type,? Izv. Akad. Nauk SSSR, Ser. Mat.,22, No. 5, 667?704 (1958).
2. E. S. Sabinina, ?On a certain class of quasilinear parabolic equations not solvable with respect to the time derivative,? Sib. Mat. Zh.,6, No. 5, 1074?1100 (1965).
3. A. S. Kalashnikov, ?On the equations of the nonstationary filtration type with an infinite rate propagation of perturbations,? Vestn. Mosk. Univ., Ser. I, Mat. Mekh., No. 6, 45?49 (1972).
4. B. F. Knerr, ?The porous medium equation in one domain,? Trans. Am. Math. Soc.,234, No. 2, 381?415 (1977).
5. J.-L. Lions, Quelques Methodes de Resolution des Problemes aux Limites Nonlineaires, Dunod, Gauthier-Villars, Paris (1969).