@article{TAC_2010_23_a5,
     author = {Sandra Mantovani and Giuseppe Metere},
     title = {Internal crossed modules and  {Peiffer} {Condition}},
     journal = {Theory and applications of categories},
     pages = {113--135},
     publisher = {mathdoc},
     volume = {23},
     year = {2010},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/TAC_2010_23_a5/}
}