@article{GDZPPN002061902, title = {Bicartesian Squares of Nilpotent Groups.}, journal = {Commentarii mathematici Helvetici}, volume = {50}, year = {1975}, pages = {477-492}, zbl = {0325.20031}, url = {http://dml.mathdoc.fr/item/GDZPPN002061902} }
Mislin, Guido; Hilton, Peter. Bicartesian Squares of Nilpotent Groups.. Commentarii mathematici Helvetici, Tome 50 (1975) pp. 477-492. http://gdmltest.u-ga.fr/item/GDZPPN002061902/