@article{RCM_1972__6_181595,
     author = {Daniel Lehmann},
     title = {Quelques probl\`emes de classes caract\'eristiques secondaires},
     journal = {Revista colombiana de matematicas},
     pages = {116--124},
     year = {1972},
     volume = {6},
     zbl = {0253.57009},
     url = {http://geodesic.mathdoc.fr/item/RCM_1972__6_181595/}
}