@article{MZ_1973__133_171963,
     author = {John W. Rutter},
     title = {A {Drived} {Homotopy} {Product.}},
     journal = {Mathematische Zeitschrift},
     pages = {343--356},
     publisher = {mathdoc},
     volume = {133},
     year = {1973},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/MZ_1973__133_171963/}
}