@article{10_1017_S0017089500003608,
     author = {Gundlach, Karl-Bernhard},
     title = {On the representation of a number as a sum of squares},
     journal = {Glasgow mathematical journal},
     pages = {173--197},
     year = {1978},
     volume = {19},
     number = {2},
     doi = {10.1017/S0017089500003608},
     url = {http://geodesic.mathdoc.fr/articles/10.1017/S0017089500003608/}
}