@article{INTG_1975_7_a5,
     author = {M. A. Akivis},
     title = {Closed $G$-structures on a~differentiable manifold},
     journal = {Itogi Nauki i Tekhniki. Seriya Problemy Geometrii. Trudy Geometricheskogo Seminara},
     pages = {69--79},
     publisher = {mathdoc},
     volume = {7},
     year = {1975},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/INTG_1975_7_a5/}
}