@article{NUMA_1991__59_8_133565,
     author = {Gene H. Golub and Urs von Matt},
     title = {Quadratically constrained least squares and quadratic problems.},
     journal = {Numerische Mathematik},
     pages = {561--580},
     publisher = {mathdoc},
     volume = {59},
     number = {8},
     year = {1991},
     zbl = {0745.65029},
     url = {http://geodesic.mathdoc.fr/item/NUMA_1991__59_8_133565/}
}