@article{CMH_1969__44_139381,
     author = {R. de Sapio},
     title = {Differential {Structures} on a {Product} of {Spheres.}},
     journal = {Commentarii mathematici Helvetici},
     pages = {61--69},
     publisher = {mathdoc},
     volume = {44},
     year = {1969},
     zbl = {0162.55303},
     url = {http://geodesic.mathdoc.fr/item/CMH_1969__44_139381/}
}