@article{CMH_1955__29_139091,
     author = {J.H.C. Whitehead and E.H. Spanier},
     title = {On fibre spaces in which the fibre is contractible.},
     journal = {Commentarii mathematici Helvetici},
     pages = {1--8},
     publisher = {mathdoc},
     volume = {29},
     year = {1955},
     zbl = {0064.41601},
     url = {http://geodesic.mathdoc.fr/item/CMH_1955__29_139091/}
}