@article{10_4064_fm_64_1_99_104,
     author = {J. Hempel and D. McMillan},
     title = {Covering three-manifolds with open cells},
     journal = {Fundamenta Mathematicae},
     pages = {99--104},
     publisher = {mathdoc},
     volume = {64},
     number = {1},
     year = {1969},
     doi = {10.4064/fm-64-1-99-104},
     language = {en},
     url = {http://geodesic.mathdoc.fr/articles/10.4064/fm-64-1-99-104/}
}