@article{TAC_2001_8_a21,
     author = {J.R.B. Cockett and Stephen Lack},
     title = {The extensive completion of a distributive category},
     journal = {Theory and applications of categories},
     pages = {541--554},
     publisher = {mathdoc},
     volume = {8},
     year = {2001},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/TAC_2001_8_a21/}
}