Qualitative analysis of a quadratic system in the large / by Cai Suilin ; [transl. from the Chinese by Zhang Hongfei ... et al.]Regularity properties of a doubly degenerate equation in hydrology / C.J. van Duijn and Zhang HongfeiOn a class of similarity solutions of the equation ut=(|u|m-1 ux)x with m>-1 / C.J. van Duijn, S.M. Gomes, Zhang Hongfei