Bistable pulsating fronts for reaction-diffusion equations in a periodic habitat Weiwei DingFrancois HamelXianfeng Zhao Indiana University Mathematics Journal 2017 text pdf 10.1512/iumj.2017.66.6070 10.1512/iumj.2017.66.6070 en Indiana Univ. Math. J. 66 (2017) 1189 - 1265 state-of-the-art mathematics http://iumj.org/access/