@article{TIMB_2006_14_1_a5,
     author = {A. V. Guminskaya},
     title = {Index of zero and index at infinity for vector fields with nonnegative operators},
     journal = {Trudy Instituta matematiki},
     pages = {44--50},
     publisher = {mathdoc},
     volume = {14},
     number = {1},
     year = {2006},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/TIMB_2006_14_1_a5/}
}