@article{10_21136_CMJ_1969_100873,
     author = {Skula, Ladislav},
     title = {System of layers of an ordered set},
     journal = {Czechoslovak Mathematical Journal},
     pages = {27--41},
     publisher = {mathdoc},
     volume = {19},
     number = {1},
     year = {1969},
     doi = {10.21136/CMJ.1969.100873},
     mrnumber = {0236072},
     zbl = {0176.28503},
     language = {en},
     url = {http://geodesic.mathdoc.fr/articles/10.21136/CMJ.1969.100873/}
}