TY  - BOOK
AU  - Nayfeh, Ali Hasan
TI  - Perturbation methods
SN  - 471399175
U1  - 629.101515 
PY  - 1973///
CY  - New York
PB  - John Wiley & Sons
KW  - Perturbation (Mathematics) asmptotic expensions
ER  -