@article{CMUC_1972_13_1_a7,
     author = {Bican, Ladislav},
     title = {Projective purities},
     journal = {Commentationes Mathematicae Universitatis Carolinae},
     pages = {99--107},
     year = {1972},
     volume = {13},
     number = {1},
     mrnumber = {0314907},
     zbl = {0238.16023},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/CMUC_1972_13_1_a7/}
}