@article{GDZPPN002057077, title = {On the existence of a connection with curvature zero.}, journal = {Commentarii mathematici Helvetici}, volume = {32}, year = {1957}, pages = {215-223}, zbl = {0196.25101}, url = {http://dml.mathdoc.fr/item/GDZPPN002057077} }
Milnor, John. On the existence of a connection with curvature zero.. Commentarii mathematici Helvetici, Tome 32 (1957) pp. 215-223. http://gdmltest.u-ga.fr/item/GDZPPN002057077/