@article{CMH_1956__31_139141,
     author = {N.E. Steenrod},
     title = {Cohomology {Operations} {Derived} from the {Symmetric} {Group.}},
     journal = {Commentarii mathematici Helvetici},
     pages = {195--218},
     publisher = {mathdoc},
     volume = {31},
     year = {1956},
     zbl = {0077.16701},
     url = {http://geodesic.mathdoc.fr/item/CMH_1956__31_139141/}
}