@article{IVM_1967_8_a10, author = {Sh. R. Sharipov}, title = {The number of exceptional directions and singular lines}, journal = {Izvesti\^a vys\v{s}ih u\v{c}ebnyh zavedenij. Matematika}, pages = {94--99}, publisher = {mathdoc}, number = {8}, year = {1967}, language = {ru}, url = {http://geodesic.mathdoc.fr/item/IVM_1967_8_a10/} }