@article{GT_2013_17_1_a14,
     author = {Kennard, Lee},
     title = {On the {Hopf} conjecture with symmetry},
     journal = {Geometry & topology},
     pages = {563--593},
     publisher = {mathdoc},
     volume = {17},
     number = {1},
     year = {2013},
     doi = {10.2140/gt.2013.17.563},
     url = {http://geodesic.mathdoc.fr/articles/10.2140/gt.2013.17.563/}
}