@article{IVM_1977_1_a20,
     author = {Ya. L. Shapiro and N. I. Zhukova},
     title = {Reducible $k$-sheeted structures},
     journal = {Izvesti\^a vys\v{s}ih u\v{c}ebnyh zavedenij. Matematika},
     pages = {144--147},
     publisher = {mathdoc},
     number = {1},
     year = {1977},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/IVM_1977_1_a20/}
}