@article{RM_1984_39_5_a5,
     author = {S. P. Novikov},
     title = {The~analytic generalized {Hopf} invariant. {Many-valued} functionals},
     journal = {Trudy Matematicheskogo Instituta imeni V.A. Steklova},
     pages = {113--124},
     publisher = {mathdoc},
     volume = {39},
     number = {5},
     year = {1984},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/RM_1984_39_5_a5/}
}