@article{10_4153_CMB_1988_037_x,
     author = {Hansen, Vagn Lundsgaard},
     title = {On {Steenrod} {Bundles} and the van {Kampen} {Theorem}},
     journal = {Canadian mathematical bulletin},
     pages = {241--249},
     year = {1988},
     volume = {31},
     number = {2},
     doi = {10.4153/CMB-1988-037-x},
     url = {http://geodesic.mathdoc.fr/articles/10.4153/CMB-1988-037-x/}
}