@article{IM2_1967_1_5_a6,
     author = {V. L. Golo},
     title = {On an invariant of open manifolds},
     journal = {Izvestiya. Mathematics },
     pages = {1041--1054},
     publisher = {mathdoc},
     volume = {1},
     number = {5},
     year = {1967},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/IM2_1967_1_5_a6/}
}