00349nam a2200133 a 450000500170000002000150001708200150003210000200004724500490006725000120011626000290012830000250015749000330018220251203110738.0  a8181281837  a515.3bPER  aPerko, Lawrence  aDifferential equations and dynamical systems  a3rd ed.  aNew YorkbSpringerc2001  axiv, 555p.c26 cm PB  aTexts in Applied Mathematics