@article{IVM_1975_1_a14,
     author = {R. M. Geidel'man},
     title = {Multidimensional ruled surfaces with holonomic families of $L^{\hat a}_s$-planes, and focal transforms of a~surface},
     journal = {Izvesti\^a vys\v{s}ih u\v{c}ebnyh zavedenij. Matematika},
     pages = {97--100},
     publisher = {mathdoc},
     number = {1},
     year = {1975},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/IVM_1975_1_a14/}
}