@article{TAC_1999_5_a0,
     author = {Peter Johnstone},
     title = {A note on discrete {Conduch\'e} fibrations},
     journal = {Theory and applications of categories},
     pages = {1--11},
     year = {1999},
     volume = {5},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/TAC_1999_5_a0/}
}