@article{10_4153_CMB_2017_057_6,
     author = {Bu, Shangquan and Cai, Gang},
     title = {Periodic {Solutions} of {Second} {Order} {Degenerate} {Differential} {Equations} with {Delay} in {Banach} {Spaces}},
     journal = {Canadian mathematical bulletin},
     pages = {717--737},
     year = {2018},
     volume = {61},
     number = {4},
     doi = {10.4153/CMB-2017-057-6},
     url = {http://geodesic.mathdoc.fr/articles/10.4153/CMB-2017-057-6/}
}