@article{TAC_2001_9_a7,
     author = {Dominique Bourn and Marino Gran},
     title = {Centrality and normality in protomodular categories},
     journal = {Theory and applications of categories},
     pages = {151--165},
     publisher = {mathdoc},
     volume = {9},
     year = {2001},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/TAC_2001_9_a7/}
}