@article{CMH_1968__43_139352,
     author = {J. Milnor},
     title = {On {Characteristic} {Classes} for {Spherical} {Fibre} {Spaces.}},
     journal = {Commentarii mathematici Helvetici},
     pages = {51--77},
     publisher = {mathdoc},
     volume = {43},
     year = {1968},
     zbl = {0153.53403},
     url = {http://geodesic.mathdoc.fr/item/CMH_1968__43_139352/}
}