@article{TAC_2009_22_a8,
     author = {Eric Goubault and Emmanuel Haucourt and Sanjeevi Krishnan},
     title = {Covering space theory for directed topology},
     journal = {Theory and applications of categories},
     pages = {252--268},
     publisher = {mathdoc},
     volume = {22},
     year = {2009},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/TAC_2009_22_a8/}
}