@article{JMPA_1845_1_10__169_0,
     author = {Liouville, J.},
     title = {Sur les deux formes $x^2+y^2+z^2+t^2$,$x^2+2y^2+3z^2+6t^2$},
     journal = {Journal de Math\'ematiques Pures et Appliqu\'ees},
     pages = {169--170},
     publisher = {Gauthier-Villars},
     volume = {1e s{\'e}rie, 10},
     year = {1845},
     language = {fr},
     url = {http://www.numdam.org/item/JMPA_1845_1_10__169_0/}
}