@article{1248269777, author = {Filipin, Alan}, title = {On the Size of Sets in Which $xy + 4$ is Always a Square}, journal = {Rocky Mountain J. Math.}, volume = {39}, number = {1}, year = {2009}, pages = { 1195-1224}, language = {en}, url = {http://dml.mathdoc.fr/item/1248269777} }
Filipin, Alan. On the Size of Sets in Which $xy + 4$ is Always a Square. Rocky Mountain J. Math., Tome 39 (2009) no. 1, pp. 1195-1224. http://gdmltest.u-ga.fr/item/1248269777/