[1] Ackerberg, R.C.and R.E.O'Malley, Jr., Boundarylayer problem exhibiting resonance, Studies Appl.Meth., 49, 3(1970), 277-295.
[2] Watt, A.M., A singular perturbation problem with a turning point, Bull.Austral.Math.Soc.5(1971), 61-73.
[3] Cook, L.P.and W.Eckhaus, Resonance in a boundary value problem of singular perturbation type, Studies in Appl.Math., 7, 2(1973), 129-139.
[4] Matkowsky, B.J., On boundary layer problems exhibiting resonance, SIAM Rev., 17(1975), 82-100;Errata, Ibid., 18(1976), 112.
[5] Olver, F.W.J., Sufficient conditions for Ackerberg-O'Malley resonance, SIAM J.Math.Anal., 9(1978), 328-355．