@article{PDM_2009_4_a1,
     author = {N. G. Parvatov},
     title = {About invariants for some classes of quasimonotonic functions on a~semilattice},
     journal = {Prikladna\^a diskretna\^a matematika},
     pages = {21--27},
     publisher = {mathdoc},
     number = {4},
     year = {2009},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/PDM_2009_4_a1/}
}