@article{IM_1969__8_141980,
     author = {A.H.M. LEVELT},
     title = {Foncteurs exacts \`a gauche.},
     journal = {Inventiones mathematicae},
     pages = {114--140},
     year = {1969},
     volume = {8},
     zbl = {0194.01905},
     url = {http://geodesic.mathdoc.fr/item/IM_1969__8_141980/}
}