@article{IM_1973__19_142199,
     author = {Friedrich Ulmer},
     title = {A {Flatness} {Criterion} in {Grothendieck} {Categories.}},
     journal = {Inventiones mathematicae},
     pages = {331--336},
     publisher = {mathdoc},
     volume = {19},
     year = {1973},
     zbl = {0257.18020},
     url = {http://geodesic.mathdoc.fr/item/IM_1973__19_142199/}
}