MR0961749
Hara, Tadayuki and Yoneyama, Toshiaki
Tadayuki HARA and Toshiaki YONEYAMA
On the global center of generalized Li\'enard equation and its application to stability problems. {II}
Funkcialaj Ekvacioj. Serio Internacia
31
1988
221--225
http://fe.math.kobe-u.ac.jp/FE/Free/vol31/fe31-2-4.pdf
http://fe.math.kobe-u.ac.jp/FE/FE_pdf_with_bookmark/FE31-34-en_KML/fe31-221-225/fe31-221-225.pdf
http://www.ams.org/mathscinet-getitem?mr=MR0961749
fe31-221-225
1988
On the Global Center of Generalized Liénard Equation and its Application to Stability Problems II
Hara, Tadayuki and Yoneyama, Toshiaki
Hara, Tadayuki and Yoneyama, Toshiaki
1
Coddington, E. A.; Levinson, N.
Theory of ordinary differential equations
McGraw-Hill, New York
1955
MR0069338