@article{COCV_2021__27_1_A26_0,
     author = {Liu, Hanbing and Wang, Gengsheng},
     title = {Second order optimality conditions for periodic optimal control problems governed by semilinear parabolic differential equations},
     journal = {ESAIM: Control, Optimisation and Calculus of Variations},
     year = {2021},
     publisher = {EDP-Sciences},
     volume = {27},
     doi = {10.1051/cocv/2021028},
     language = {en},
     url = {https://www.numdam.org/articles/10.1051/cocv/2021028/}
}