@article{10_4153_CMB_1978_051_4,
     author = {Duggal, K. L.},
     title = {On {Almost} {Contingent} {Manifolds} of {Second} {Class} with {Applications} in {Relativity}},
     journal = {Canadian mathematical bulletin},
     pages = {289--295},
     year = {1978},
     volume = {21},
     number = {3},
     doi = {10.4153/CMB-1978-051-4},
     url = {http://geodesic.mathdoc.fr/articles/10.4153/CMB-1978-051-4/}
}