@article{MS2_1974__35_166381,
     author = {Vagn Lundsgaard Hansen},
     title = {On the {Space} of {Maps} of a {Closed} {Surface} into the {2-Sphere.}},
     journal = {Mathematica Scandinavica},
     pages = {149--158},
     publisher = {mathdoc},
     volume = {35},
     year = {1974},
     zbl = {0299.55017},
     url = {http://geodesic.mathdoc.fr/item/MS2_1974__35_166381/}
}