@article{CMUC_1989_30_4_a25,
     author = {Yun, Ziqiu},
     title = {On a problem of {J.} {Nagata}},
     journal = {Commentationes Mathematicae Universitatis Carolinae},
     pages = {811--815},
     year = {1989},
     volume = {30},
     number = {4},
     mrnumber = {1045914},
     zbl = {0692.54017},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/CMUC_1989_30_4_a25/}
}