@article{TAC_2007_18_a17,
     author = {Lutz Strassburger},
     title = {On the axiomatisation of {Boolean} categories  with and without medial},
     journal = {Theory and applications of categories},
     pages = {536--601},
     publisher = {mathdoc},
     volume = {18},
     year = {2007},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/TAC_2007_18_a17/}
}