@article{TAC_2007_18_a19,
     author = {M. Menni and N. Sabadini and R. F. C. Walters},
     title = {A universal property of the monoidal 2-category of cospans of ordinals and 
surjections},
     journal = {Theory and applications of categories},
     pages = {631--653},
     publisher = {mathdoc},
     volume = {18},
     year = {2007},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/TAC_2007_18_a19/}
}