Song, Bin Heng et Jian, Huai Yu, Fundamental Solution of the Anisotropic Porous Medium Equation, Acta mathematica Sinica. English series (Print) , 21(5), 2005, pp. 1183-1190
We establish the existence of fundamental solutions for the anisotropic porous medium equation, ut=.ni=1(umi)xixi in .n . (0,.), where m 1,m 2, . . . , and m n are positive constants satisfying min1.i.n{mi}.1,.ni=1mi>n.2, and max1.i.n{mi}.1n(2+.ni=1mi).