@article{1183424767,
author = {Sommerville, D. M. Y.},
title = {Quadratic systems of circles in non-euclidean geometry},
journal = {Bull. Amer. Math. Soc.},
volume = {26},
number = {3},
year = {1919},
pages = { 161-173},
language = {en},
url = {http://dml.mathdoc.fr/item/1183424767}
}
Sommerville, D. M. Y. Quadratic systems of circles in non-euclidean geometry. Bull. Amer. Math. Soc., Tome 26 (1919) no. 3, pp. 161-173. http://gdmltest.u-ga.fr/item/1183424767/