@article{IVM_2001_9_a4,
     author = {Guo Wenbin},
     title = {On a~problem in the theory of step formations},
     journal = {Izvesti\^a vys\v{s}ih u\v{c}ebnyh zavedenij. Matematika},
     pages = {33--37},
     publisher = {mathdoc},
     number = {9},
     year = {2001},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/IVM_2001_9_a4/}
}