@article{GDZPPN00207883X, title = {Two Non-Negative Quadratic Forms.}, journal = {Elemente der Mathematik}, volume = {28}, year = {1973}, pages = {141-146}, zbl = {0266.52006}, url = {http://dml.mathdoc.fr/item/GDZPPN00207883X} }
Klamkin, Murray S. Two Non-Negative Quadratic Forms.. Elemente der Mathematik, Tome 28 (1973) pp. 141-146. http://gdmltest.u-ga.fr/item/GDZPPN00207883X/