Approximate Analytical Solution of the Nonlinear Diffusion Equation for Arbitrary Boundary Conditions - Parlange, J.-Y.; Hogarth, W. L.; Parlange, M. B.; Haverkamp, R.; Barry, D. A.; Ross, P. J.; Steenhuis, T. S. (Springer, 1998)
http://dx.doi.org/10.1023/A:1006508721609
Keywords: TE-TZ; ZG