@article{JAC_2014__39_3_a4,
     author = {Katz, Eric},
     title = {A non-abelian analogue of {Whitney's} 2-isomorphism theorem},
     journal = {Journal of Algebraic Combinatorics},
     pages = {683--690},
     publisher = {mathdoc},
     volume = {39},
     number = {3},
     year = {2014},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/JAC_2014__39_3_a4/}
}