TY  - BOOK
AU  - Bautin N N
TI  - On the number of limit cycles which appear with the variation of coefficients from an equilibrium position of focus or center type
U1  - 510T 
PY  - 1953///
CY  - Providence
PB  - AMS
KW  - Mathematics
N1  - Tr from Matematicskii Sbornik (NS) 30(72), 181-196, 1952
ER  -