@article{10_4064_cm_28_1_1_5,
     author = {Klaus Kaiser},
     title = {On generalized projective classes},
     journal = {Colloquium Mathematicum},
     pages = {1--5},
     publisher = {mathdoc},
     volume = {28},
     number = {1},
     year = {1973},
     doi = {10.4064/cm-28-1-1-5},
     language = {en},
     url = {http://geodesic.mathdoc.fr/articles/10.4064/cm-28-1-1-5/}
}