On the number of limit cycles which appear with the variation of coefficients from an equilibrium position of focus or center type
19p Tr from Matematicskii Sbornik (NS) 30(72), 181-196, 1952
Phone no. 91-33-2575 2100, Fax no. 91-33-2578 1412, ksatpathy@isical.ac.in
