@article{CMH_1972__47_139524,
     author = {Douglas C. Ravenel},
     title = {A {Definition} of {Exotic} {Characteristic} {Classes} of {Spherical} {Fibrations}},
     journal = {Commentarii mathematici Helvetici},
     pages = {421--436},
     publisher = {mathdoc},
     volume = {47},
     year = {1972},
     zbl = {0258.55008},
     url = {http://geodesic.mathdoc.fr/item/CMH_1972__47_139524/}
}