1. A. S. Besicovitch, Almost Periodic Functions (Cambridge Univ. Press, Cambridge, 1932).
2. J. Carrillo, ‘‘Entropy solutions for nonlinear degenerate problems,’’ Arch. Ration. Mech. Anal. 147, 269–361 (1999).
3. G.-Q. Chen and B. Perthame, ‘‘Well-posedness for non-isotropic degenerate parabolic-hyperbolic equations,’’ Ann. Inst. Poincaré Anal. Non-Lin. 20, 645–668 (2003).
4. G.-Q. Chen and B. Perthame, ‘‘Large-time behavior of periodic entropy solutions to anisotropic degenerate parabolic-hyperbolic equations,’’ Proc. Am. Math. Soc. 137, 3003–3011 (2009).
5. N. Danford and J. T. Schwartz, Linear Operators. General Theory. Part I (Interscience, New York, London, 1958).