@article{1077491076,
author = {Singleton, Robert},
title = {The characterization of flat projective spaces by their differential invariants},
journal = {Duke Math. J.},
volume = {5},
number = {1},
year = {1939},
pages = { 39-48},
language = {en},
url = {http://dml.mathdoc.fr/item/1077491076}
}
Singleton, Robert. The characterization of flat projective spaces by their differential invariants. Duke Math. J., Tome 5 (1939) no. 1, pp. 39-48. http://gdmltest.u-ga.fr/item/1077491076/