1. The Cauchy problem and boundary value problems for equations of the type of non-stationary filtration;Oleinik;Izv. Akad. Nauk. SSR Ser. Mat.,1958
2. On the occurrence of singularities in the solutions of the equation of nonstationary filtration;Kalishnikov;Vychisl. Mat. Mat. Fis.,1967
3. Regularity properties of flows through porous media;Aronson;SIAM Jl Appl. Math.,1969
4. Regularity properties of flows through porous media: the interface;Aronson;Archs rational Mech. Analysis,1970
5. The porous medium equation in one-dimension;Knerr;Trans. Am. math. Soc.,1977