On Singular Perturbation Problems with Several Turning Points S. Kamin Indiana University Mathematics Journal 1982 text pdf 10.1512/iumj.1982.31.31058 10.1512/iumj.1982.31.31058 en Indiana Univ. Math. J. 31 (1982) 819 - 841 state-of-the-art mathematics http://iumj.org/access/