PERIODIC SOLUTIONS OF A CLASS OF EVEN ORDER DIFFERENTIAL EQUATIONS

1Introduction1.1Theal1TIof'1.hispa;pel'istopl'ovidesufficientcon(lit,iolls1'or1.lieexisted(feofperiodicsolutjoilsof1,he21't,horderdift'erentitxleqllal,ionandthellorl--cxistcnceoflloTI--ti}ivialperio相似文献   

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