@article{PMIHES_1980__51__37_0,
     author = {Schwarz, Gerald W.},
     title = {Lifting smooth homotopies of orbit spaces},
     journal = {Publications Math\'ematiques de l'IH\'ES},
     pages = {37--135},
     publisher = {Institut des Hautes \'Etudes Scientifiques},
     volume = {51},
     year = {1980},
     mrnumber = {81h:57024},
     zbl = {0449.57009},
     language = {en},
     url = {http://www.numdam.org/item/PMIHES_1980__51__37_0/}
}