@article{1077491406,
author = {Halperin, Israel},
title = {Additivity and continuity of perspectivity},
journal = {Duke Math. J.},
volume = {5},
number = {1},
year = {1939},
pages = { 503-511},
language = {en},
url = {http://dml.mathdoc.fr/item/1077491406}
}
Halperin, Israel. Additivity and continuity of perspectivity. Duke Math. J., Tome 5 (1939) no. 1, pp. 503-511. http://gdmltest.u-ga.fr/item/1077491406/