@article{CMUC_1966_7_2_a3,
     author = {Trnkov\'a, V\v{e}ra},
     title = {Universal categories},
     journal = {Commentationes Mathematicae Universitatis Carolinae},
     pages = {143--206},
     year = {1966},
     volume = {7},
     number = {2},
     mrnumber = {0202808},
     zbl = {0163.01501},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/CMUC_1966_7_2_a3/}
}