@article{10_4153_CMB_1991_073_2,
     author = {Bulman-Fleming, Sydney},
     title = {Pullback-Flat {Acts} are {Strongly} {Flat}},
     journal = {Canadian mathematical bulletin},
     pages = {456--461},
     year = {1991},
     volume = {34},
     number = {4},
     doi = {10.4153/CMB-1991-073-2},
     url = {http://geodesic.mathdoc.fr/articles/10.4153/CMB-1991-073-2/}
}