00366nam a2200121Ia 4500082002000000100004200020245004400062260003600106300002200142490004300164500000500207700003200212  a515.35bB658.SD  aBlumen, George W. and Kumei, Sukeyuki  aSymmetries and differential equationsb  aNew YorkbSpringer-Verlagc1989  axiii, 412p. Index  aApplied Mathematical Sciences v v. 81  a  aKumei, Sukeyuki ; jt. auth.