@article{VMUMM_2015_3_a4,
     author = {M. I. Kharitonov},
     title = {The estimate of the number of permutationally-ordered sets},
     journal = {Vestnik Moskovskogo universiteta. Matematika, mehanika},
     pages = {24--28},
     publisher = {mathdoc},
     number = {3},
     year = {2015},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/VMUMM_2015_3_a4/}
}