@article{TM2_2005_VIII_2_a0,
     author = {Vladimir Jankovi\'c},
     title = {Quadratic functions in several variables},
     journal = {The Teaching of Mathematics},
     pages = {53 },
     publisher = {mathdoc},
     volume = {VIII},
     number = {2},
     year = {2005},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/TM2_2005_VIII_2_a0/}
}