@article{10_4064_aa102_2_2,
     author = {Meinhard Peters},
     title = {Sums of nine squares},
     journal = {Acta Arithmetica},
     pages = {131--135},
     publisher = {mathdoc},
     volume = {102},
     number = {2},
     year = {2002},
     doi = {10.4064/aa102-2-2},
     language = {en},
     url = {http://geodesic.mathdoc.fr/articles/10.4064/aa102-2-2/}
}