@article{CTGDC_1981__22_3_329_0,
     author = {Frei, Armin},
     title = {On the preservation of homotopy invariance by {Kan} extensions},
     journal = {Cahiers de Topologie et G\'eom\'etrie Diff\'erentielle Cat\'egoriques},
     pages = {329--336},
     publisher = {Dunod \'editeur, publi\'e avec le concours du CNRS},
     volume = {22},
     number = {3},
     year = {1981},
     mrnumber = {649080},
     zbl = {0486.18006},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/CTGDC_1981__22_3_329_0/}
}