@article{TAC_2001_8_a4,
     author = {J. R. B. Cockett and R. A. G. Seely},
     title = {Finite sum - product logic},
     journal = {Theory and applications of categories},
     pages = {63--99},
     publisher = {mathdoc},
     volume = {8},
     year = {2001},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/TAC_2001_8_a4/}
}