@article{1183498917,
author = {Bell, E. T.},
title = {The form $wx + xy + yz + zu$},
journal = {Bull. Amer. Math. Soc.},
volume = {42},
number = {12},
year = {1936},
pages = { 377-380},
language = {en},
url = {http://dml.mathdoc.fr/item/1183498917}
}
Bell, E. T. The form $wx + xy + yz + zu$. Bull. Amer. Math. Soc., Tome 42 (1936) no. 12, pp. 377-380. http://gdmltest.u-ga.fr/item/1183498917/