@article{IVM_1990_10_a1,
     author = {S. G. Leiko},
     title = {Variational problems for rotation functionals, and spin-mappings of {pseudo-Riemannian} spaces},
     journal = {Izvesti\^a vys\v{s}ih u\v{c}ebnyh zavedenij. Matematika},
     pages = {9--17},
     publisher = {mathdoc},
     number = {10},
     year = {1990},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/IVM_1990_10_a1/}
}