1. M. Ughi, “A degenerate parabolic equation modelling the spread of an epidemic,” Ann. Mat. Pura Appl., 143, 385–400 (1986).
2. M. Bertsch and R. Dal Passo, “A numerical treatment of a superdegenerate equation with application to the porous medium equation,” Quart. Appl. Math., 48, 133–152 (1990).
3. B. V. Bazalii and N. V. Krasnoshchek, “On the regularity of a solution of a problem with free boundary for the equation v
t
= (v
m
)xx,” Algebra Analiz, 12, 100–130 (2000).
4. A. S. Kalashnikov, “On some problems in the qualitative theory of nonlinear degenerate second-order parabolic equations,” Usp. Mat. Nauk, 42, 135–176 (1987).
5. O. A. Oleinik and E. V. Radkevich, “Second-order equations with nonnegative characteristic form,” VINITI Series in Mathematical Analysis, VINITI, Moscow (1971).