@article{IVM_1976_4_a9,
     author = {Ya. I. Shapiro and N. I. Zhukova},
     title = {Simple bifibrations},
     journal = {Izvesti\^a vys\v{s}ih u\v{c}ebnyh zavedenij. Matematika},
     pages = {95--104},
     publisher = {mathdoc},
     number = {4},
     year = {1976},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/IVM_1976_4_a9/}
}