@article{TAC_1998_4_a7,
     author = {A. Mutlu and T. Porter},
     title = {Freeness {Conditions} for {2-Crossed} {Modules} and {Complexes}},
     journal = {Theory and applications of categories},
     pages = {174--194},
     publisher = {mathdoc},
     volume = {4},
     year = {1998},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/TAC_1998_4_a7/}
}