@article{ZNSL_1993_205_a9,
     author = {A. M. Nikitin},
     title = {On some models in differential geometry},
     journal = {Zapiski Nauchnykh Seminarov POMI},
     pages = {122--153},
     publisher = {mathdoc},
     volume = {205},
     year = {1993},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/ZNSL_1993_205_a9/}
}