@article{10_4064_ba61_1_3,
     author = {A. Schinzel},
     title = {A {Positive} {Definite} {Binary} {Quadratic} {Form
} as a {Sum} of {Five} {Squares} of {Linear} {Forms
} {(Completion} of {Mordell's} {Proof)}},
     journal = {Bulletin of the Polish Academy of Sciences. Mathematics},
     pages = {23--26},
     publisher = {mathdoc},
     volume = {61},
     number = {1},
     year = {2013},
     doi = {10.4064/ba61-1-3},
     language = {en},
     url = {http://geodesic.mathdoc.fr/articles/10.4064/ba61-1-3/}
}