Spike-layered solutions of singularly perturbed elliptic problems in a degenerate setting Manuel del PinoPatricio Felmer 35J2035B2535B40elliptic equationssingular perturbationsspikes Indiana University Mathematics Journal 1999 text pdf 10.1512/iumj.1999.48.1596 10.1512/iumj.1999.48.1596 en Indiana Univ. Math. J. 48 (1999) 883 - 898 state-of-the-art mathematics http://iumj.org/access/