00342nam a2200121Ia 4500082002000000100002400020245006600044260004200110300001900152490003900171500000500210700000500215  a515.35bG874.SP  aGroen, P. P. N. De.  aSingularly perturbed differential operators of second orderb  aAmsterdambMathematisch Centrumc1976  aix, 159p. Ref.  aMathematical centre tractsv v. 68  a  a