中国科学院数学与系统科学研究院期刊网
AMS
Periodic Solutions of a Class of Second Order Functional Differential Equations
Zheng Qiu ZHANG, Zhi Cheng WANG
Acta Mathematica Sinica . 2005, (1): 95 -108 .  DOI: 10.1007/s10114-004-0404-5