@article{1181073161, author = {Cordes, C.M. and Foreman, D.L.}, title = {The square class invariant}, journal = {Rocky Mountain J. Math.}, volume = {20}, number = {4}, year = {1990}, pages = { 91-98}, language = {en}, url = {http://dml.mathdoc.fr/item/1181073161} }
Cordes, C.M.; Foreman, D.L. The square class invariant. Rocky Mountain J. Math., Tome 20 (1990) no. 4, pp. 91-98. http://gdmltest.u-ga.fr/item/1181073161/