@article{ZNSL_2001_279_a7,
     author = {D. V. Ivanov},
     title = {Totally geodesic subsets in the variety of directions of physical space},
     journal = {Zapiski Nauchnykh Seminarov POMI},
     pages = {141--153},
     publisher = {mathdoc},
     volume = {279},
     year = {2001},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/ZNSL_2001_279_a7/}
}