@article{1183415369,
author = {Thompson, H. D.},
title = {Focal Properties of Surfaces of the Second Order},
journal = {Bull. Amer. Math. Soc.},
volume = {4},
number = {8},
year = {1898},
pages = { 405-407},
language = {en},
url = {http://dml.mathdoc.fr/item/1183415369}
}
Thompson, H. D. Focal Properties of Surfaces of the Second Order. Bull. Amer. Math. Soc., Tome 4 (1898) no. 8, pp. 405-407. http://gdmltest.u-ga.fr/item/1183415369/