@article{MZ_1972__129_171830,
     author = {Agnes Chi-Ling Hasu},
     title = {A {Characterization} of the {Hopf} {Map} by {Stretch.}},
     journal = {Mathematische Zeitschrift},
     pages = {195--206},
     publisher = {mathdoc},
     volume = {129},
     year = {1972},
     zbl = {0235.53022},
     url = {http://geodesic.mathdoc.fr/item/MZ_1972__129_171830/}
}