@article{IM_1967__3_141879,
     author = {E. THOMAS},
     title = {Fields of {Tangent} {k-Planes} on {Manifolds.}},
     journal = {Inventiones mathematicae},
     pages = {334--347},
     publisher = {mathdoc},
     volume = {3},
     year = {1967},
     zbl = {0162.55402},
     url = {http://geodesic.mathdoc.fr/item/IM_1967__3_141879/}
}