@article{IVM_1968_4_a12,
     author = {S. E. Tychinina},
     title = {Stratifiable pairs of congruences of planes in $P_5$},
     journal = {Izvesti\^a vys\v{s}ih u\v{c}ebnyh zavedenij. Matematika},
     pages = {77--86},
     publisher = {mathdoc},
     number = {4},
     year = {1968},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/IVM_1968_4_a12/}
}