@article{10_21136_CMJ_2019_0197_18,
     author = {Sun, Yingcai and Chen, Min},
     title = {Acyclic 4-choosability of planar graphs without 4-cycles},
     journal = {Czechoslovak Mathematical Journal},
     pages = {161--178},
     publisher = {mathdoc},
     volume = {70},
     number = {1},
     year = {2020},
     doi = {10.21136/CMJ.2019.0197-18},
     mrnumber = {4078351},
     language = {en},
     url = {http://geodesic.mathdoc.fr/articles/10.21136/CMJ.2019.0197-18/}
}