@article{CMJ_2003__53_2_a9,
     author = {Jung, Hyung Chan and Lee, Jeh Gwon},
     title = {On the jump number of lexicographic sums of ordered sets},
     journal = {Czechoslovak Mathematical Journal},
     pages = {343--349},
     publisher = {mathdoc},
     volume = {53},
     number = {2},
     year = {2003},
     mrnumber = {1983456},
     zbl = {1024.06001},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/CMJ_2003__53_2_a9/}
}