00371nam a2200121 a 450000500170000002000180001708200160003510000190005124501090007026000240017930000250020370000210022820251203111032.0  a9788181289063  a515.35bBEN  aBender, carl M  aAdvanced mathematical methods for scientists and engineers Ibasymptotic methods and perturbation theory  aUSAbSpringerc2008  axiv,593p.c22cm.cPB  aOrszag, steven A