@article{GDZPPN002059576,
title = {Stable Secondary Cohomology Operations.},
journal = {Commentarii mathematici Helvetici},
volume = {44},
year = {1969},
pages = {341-353},
zbl = {0199.33202},
url = {http://dml.mathdoc.fr/item/GDZPPN002059576}
}
Harper, John R. Stable Secondary Cohomology Operations.. Commentarii mathematici Helvetici, Tome 44 (1969) pp. 341-353. http://gdmltest.u-ga.fr/item/GDZPPN002059576/