@article{GDZPPN002288583, title = {Operators and Cooperators in Homotopy Theory.}, journal = {Mathematische Annalen}, volume = {141}, year = {1960}, pages = {1-21}, zbl = {0094.17301}, url = {http://dml.mathdoc.fr/item/GDZPPN002288583} }
ECKMANN, B.; HILTON, P.J. Operators and Cooperators in Homotopy Theory.. Mathematische Annalen, Tome 141 (1960) pp. 1-21. http://gdmltest.u-ga.fr/item/GDZPPN002288583/