@article{JEMS_2016_18_7_a2,
     author = {Claus Scheiderer},
     title = {Sums of squares of polynomials with rational coefficients},
     journal = {Journal of the European Mathematical Society},
     pages = {1495--1513},
     publisher = {mathdoc},
     volume = {18},
     number = {7},
     year = {2016},
     doi = {10.4171/jems/620},
     url = {http://geodesic.mathdoc.fr/articles/10.4171/jems/620/}
}