邓 瑞 娟.一类具偏差变元二阶微分方程周期解的存在性[J].重庆工商大学学报(自然科学版),2015,32(9):61-65
DENG Ruijuan. Periodic Solutions of the Second Order Differential Equation with Deviating Arguments[J]. Journal of Chongqing Technology and Business University(Natural Science Edition),2015,32(9):61-65