@article{GDZPPN002321327,
title = {Aspherical 2-Complexes and an Unsettled Problem of J. H. C. Whitehead.},
journal = {Mathematische Annalen},
volume = {255},
year = {1981},
pages = {17-38},
zbl = {0458.57001},
url = {http://dml.mathdoc.fr/item/GDZPPN002321327}
}
Huebschmann, Johannes. Aspherical 2-Complexes and an Unsettled Problem of J. H. C. Whitehead.. Mathematische Annalen, Tome 255 (1981) pp. 17-38. http://gdmltest.u-ga.fr/item/GDZPPN002321327/